NAME
----
-qm - Qemu/KVM Virtual Machine Manager
+qm - QEMU/KVM Virtual Machine Manager
SYNOPSIS
-----------
endif::manvolnum[]
ifndef::manvolnum[]
-Qemu/KVM Virtual Machines
+QEMU/KVM Virtual Machines
=========================
:pve-toplevel:
endif::manvolnum[]
// http://pve.proxmox.com/wiki/KVM
// http://pve.proxmox.com/wiki/Qemu_Server
-Qemu (short form for Quick Emulator) is an open source hypervisor that emulates a
-physical computer. From the perspective of the host system where Qemu is
-running, Qemu is a user program which has access to a number of local resources
+QEMU (short form for Quick Emulator) is an open source hypervisor that emulates a
+physical computer. From the perspective of the host system where QEMU is
+running, QEMU is a user program which has access to a number of local resources
like partitions, files, network cards which are then passed to an
emulated computer which sees them as if they were real devices.
A guest operating system running in the emulated computer accesses these
-devices, and runs as it were running on real hardware. For instance you can pass
-an iso image as a parameter to Qemu, and the OS running in the emulated computer
-will see a real CDROM inserted in a CD drive.
+devices, and runs as if it were running on real hardware. For instance, you can pass
+an ISO image as a parameter to QEMU, and the OS running in the emulated computer
+will see a real CD-ROM inserted into a CD drive.
-Qemu can emulate a great variety of hardware from ARM to Sparc, but {pve} is
+QEMU can emulate a great variety of hardware from ARM to Sparc, but {pve} is
only concerned with 32 and 64 bits PC clone emulation, since it represents the
overwhelming majority of server hardware. The emulation of PC clones is also one
of the fastest due to the availability of processor extensions which greatly
-speed up Qemu when the emulated architecture is the same as the host
+speed up QEMU when the emulated architecture is the same as the host
architecture.
NOTE: You may sometimes encounter the term _KVM_ (Kernel-based Virtual Machine).
-It means that Qemu is running with the support of the virtualization processor
-extensions, via the Linux kvm module. In the context of {pve} _Qemu_ and
-_KVM_ can be used interchangeably as Qemu in {pve} will always try to load the kvm
+It means that QEMU is running with the support of the virtualization processor
+extensions, via the Linux KVM module. In the context of {pve} _QEMU_ and
+_KVM_ can be used interchangeably, as QEMU in {pve} will always try to load the KVM
module.
-Qemu inside {pve} runs as a root process, since this is required to access block
+QEMU inside {pve} runs as a root process, since this is required to access block
and PCI devices.
Emulated devices and paravirtualized devices
--------------------------------------------
-The PC hardware emulated by Qemu includes a mainboard, network controllers,
-scsi, ide and sata controllers, serial ports (the complete list can be seen in
+The PC hardware emulated by QEMU includes a motherboard, network controllers,
+SCSI, IDE and SATA controllers, serial ports (the complete list can be seen in
the `kvm(1)` man page) all of them emulated in software. All these devices
are the exact software equivalent of existing hardware devices, and if the OS
running in the guest has the proper drivers it will use the devices as if it
-were running on real hardware. This allows Qemu to runs _unmodified_ operating
+were running on real hardware. This allows QEMU to run _unmodified_ operating
systems.
This however has a performance cost, as running in software what was meant to
run in hardware involves a lot of extra work for the host CPU. To mitigate this,
-Qemu can present to the guest operating system _paravirtualized devices_, where
-the guest OS recognizes it is running inside Qemu and cooperates with the
+QEMU can present to the guest operating system _paravirtualized devices_, where
+the guest OS recognizes it is running inside QEMU and cooperates with the
hypervisor.
-Qemu relies on the virtio virtualization standard, and is thus able to present
+QEMU relies on the virtio virtualization standard, and is thus able to present
paravirtualized virtio devices, which includes a paravirtualized generic disk
controller, a paravirtualized network card, a paravirtualized serial port,
a paravirtualized SCSI controller, etc ...
-It is highly recommended to use the virtio devices whenever you can, as they
-provide a big performance improvement. Using the virtio generic disk controller
-versus an emulated IDE controller will double the sequential write throughput,
-as measured with `bonnie++(8)`. Using the virtio network interface can deliver
-up to three times the throughput of an emulated Intel E1000 network card, as
-measured with `iperf(1)`. footnote:[See this benchmark on the KVM wiki
-http://www.linux-kvm.org/page/Using_VirtIO_NIC]
+TIP: It is *highly recommended* to use the virtio devices whenever you can, as
+they provide a big performance improvement and are generally better maintained.
+Using the virtio generic disk controller versus an emulated IDE controller will
+double the sequential write throughput, as measured with `bonnie++(8)`. Using
+the virtio network interface can deliver up to three times the throughput of an
+emulated Intel E1000 network card, as measured with `iperf(1)`. footnote:[See
+this benchmark on the KVM wiki https://www.linux-kvm.org/page/Using_VirtIO_NIC]
[[qm_virtual_machines_settings]]
General Settings
~~~~~~~~~~~~~~~~
-[thumbnail="gui-create-vm-general.png"]
+[thumbnail="screenshot/gui-create-vm-general.png"]
General settings of a VM include
OS Settings
~~~~~~~~~~~
-[thumbnail="gui-create-vm-os.png"]
+[thumbnail="screenshot/gui-create-vm-os.png"]
-When creating a VM, setting the proper Operating System(OS) allows {pve} to
-optimize some low level parameters. For instance Windows OS expect the BIOS
-clock to use the local time, while Unix based OS expect the BIOS clock to have
-the UTC time.
+When creating a virtual machine (VM), setting the proper Operating System(OS)
+allows {pve} to optimize some low level parameters. For instance Windows OS
+expect the BIOS clock to use the local time, while Unix based OS expect the
+BIOS clock to have the UTC time.
+[[qm_system_settings]]
+System Settings
+~~~~~~~~~~~~~~~
+
+On VM creation you can change some basic system components of the new VM. You
+can specify which xref:qm_display[display type] you want to use.
+[thumbnail="screenshot/gui-create-vm-system.png"]
+Additionally, the xref:qm_hard_disk[SCSI controller] can be changed.
+If you plan to install the QEMU Guest Agent, or if your selected ISO image
+already ships and installs it automatically, you may want to tick the 'QEMU
+Agent' box, which lets {pve} know that it can use its features to show some
+more information, and complete some actions (for example, shutdown or
+snapshots) more intelligently.
+
+{pve} allows to boot VMs with different firmware and machine types, namely
+xref:qm_bios_and_uefi[SeaBIOS and OVMF]. In most cases you want to switch from
+the default SeaBIOS to OVMF only if you plan to use
+xref:qm_pci_passthrough[PCIe passthrough].
+
+[[qm_machine_type]]
+
+Machine Type
+^^^^^^^^^^^^
+
+A VM's 'Machine Type' defines the hardware layout of the VM's virtual
+motherboard. You can choose between the default
+https://en.wikipedia.org/wiki/Intel_440FX[Intel 440FX] or the
+https://ark.intel.com/content/www/us/en/ark/products/31918/intel-82q35-graphics-and-memory-controller.html[Q35]
+chipset, which also provides a virtual PCIe bus, and thus may be
+desired if you want to pass through PCIe hardware.
+Additionally, you can select a xref:qm_pci_viommu[vIOMMU] implementation.
+
+Machine Version
++++++++++++++++
+
+Each machine type is versioned in QEMU and a given QEMU binary supports many
+machine versions. New versions might bring support for new features, fixes or
+general improvements. However, they also change properties of the virtual
+hardware. To avoid sudden changes from the guest's perspective and ensure
+compatibility of the VM state, live-migration and snapshots with RAM will keep
+using the same machine version in the new QEMU instance.
+
+For Windows guests, the machine version is pinned during creation, because
+Windows is sensitive to changes in the virtual hardware - even between cold
+boots. For example, the enumeration of network devices might be different with
+different machine versions. Other OSes like Linux can usually deal with such
+changes just fine. For those, the 'Latest' machine version is used by default.
+This means that after a fresh start, the newest machine version supported by the
+QEMU binary is used (e.g. the newest machine version QEMU 8.1 supports is
+version 8.1 for each machine type).
+
+[[qm_machine_update]]
+
+Update to a Newer Machine Version
++++++++++++++++++++++++++++++++++
+
+Very old machine versions might become deprecated in QEMU. For example, this is
+the case for versions 1.4 to 1.7 for the i440fx machine type. It is expected
+that support for these machine versions will be dropped at some point. If you
+see a deprecation warning, you should change the machine version to a newer one.
+Be sure to have a working backup first and be prepared for changes to how the
+guest sees hardware. In some scenarios, re-installing certain drivers might be
+required. You should also check for snapshots with RAM that were taken with
+these machine versions (i.e. the `runningmachine` configuration entry).
+Unfortunately, there is no way to change the machine version of a snapshot, so
+you'd need to load the snapshot to salvage any data from it.
[[qm_hard_disk]]
Hard Disk
~~~~~~~~~
-Qemu can emulate a number of storage controllers:
+[[qm_hard_disk_bus]]
+Bus/Controller
+^^^^^^^^^^^^^^
+QEMU can emulate a number of storage controllers:
+
+TIP: It is highly recommended to use the *VirtIO SCSI* or *VirtIO Block*
+controller for performance reasons and because they are better maintained.
* the *IDE* controller, has a design which goes back to the 1984 PC/AT disk
controller. Even if this controller has been superseded by recent designs,
hardware, and can connect up to 14 storage devices. {pve} emulates by default a
LSI 53C895A controller.
+
-A SCSI controller of type _VirtIO SCSI_ is the recommended setting if you aim for
-performance and is automatically selected for newly created Linux VMs since
-{pve} 4.3. Linux distributions have support for this controller since 2012, and
-FreeBSD since 2014. For Windows OSes, you need to provide an extra iso
-containing the drivers during the installation.
+A SCSI controller of type _VirtIO SCSI single_ and enabling the
+xref:qm_hard_disk_iothread[IO Thread] setting for the attached disks is
+recommended if you aim for performance. This is the default for newly created
+Linux VMs since {pve} 7.3. Each disk will have its own _VirtIO SCSI_ controller,
+and QEMU will handle the disks IO in a dedicated thread. Linux distributions
+have support for this controller since 2012, and FreeBSD since 2014. For Windows
+OSes, you need to provide an extra ISO containing the drivers during the
+installation.
// https://pve.proxmox.com/wiki/Paravirtualized_Block_Drivers_for_Windows#During_windows_installation.
-If you aim at maximum performance, you can select a SCSI controller of type
-_VirtIO SCSI single_ which will allow you to select the *IO Thread* option.
-When selecting _VirtIO SCSI single_ Qemu will create a new controller for
-each disk, instead of adding all disks to the same controller.
* The *VirtIO Block* controller, often just called VirtIO or virtio-blk,
is an older type of paravirtualized controller. It has been superseded by the
VirtIO SCSI Controller, in terms of features.
-[thumbnail="gui-create-vm-hard-disk.png"]
+[thumbnail="screenshot/gui-create-vm-hard-disk.png"]
+
+[[qm_hard_disk_formats]]
+Image Format
+^^^^^^^^^^^^
On each controller you attach a number of emulated hard disks, which are backed
by a file or a block device residing in the configured storage. The choice of
a storage type will determine the format of the hard disk image. Storages which
present block devices (LVM, ZFS, Ceph) will require the *raw disk image format*,
-whereas files based storages (Ext4, NFS, GlusterFS) will let you to choose
+whereas files based storages (Ext4, NFS, CIFS, GlusterFS) will let you to choose
either the *raw disk image format* or the *QEMU image format*.
* the *QEMU image format* is a copy on write format which allows snapshots, and
format does not support thin provisioning or snapshots by itself, requiring
cooperation from the storage layer for these tasks. It may, however, be up to
10% faster than the *QEMU image format*. footnote:[See this benchmark for details
- http://events.linuxfoundation.org/sites/events/files/slides/CloudOpen2013_Khoa_Huynh_v3.pdf]
+ https://events.static.linuxfound.org/sites/events/files/slides/CloudOpen2013_Khoa_Huynh_v3.pdf]
* the *VMware image format* only makes sense if you intend to import/export the
disk image to other hypervisors.
+[[qm_hard_disk_cache]]
+Cache Mode
+^^^^^^^^^^
Setting the *Cache* mode of the hard drive will impact how the host system will
notify the guest systems of block write completions. The *No cache* default
means that the guest system will be notified that a write is complete when each
`zfspool`, so adding a disk image to other storages when the VM has replication
configured requires to skip replication for this disk image.
+[[qm_hard_disk_discard]]
+Trim/Discard
+^^^^^^^^^^^^
If your storage supports _thin provisioning_ (see the storage chapter in the
-{pve} guide), and your VM has a *SCSI* controller you can activate the *Discard*
-option on the hard disks connected to that controller. With *Discard* enabled,
-when the filesystem of a VM marks blocks as unused after removing files, the
-emulated SCSI controller will relay this information to the storage, which will
-then shrink the disk image accordingly.
-
-.IO Thread
-The option *IO Thread* can only be used when using a disk with the
-*VirtIO* controller, or with the *SCSI* controller, when the emulated controller
- type is *VirtIO SCSI single*.
-With this enabled, Qemu creates one I/O thread per storage controller,
-instead of a single thread for all I/O, so it increases performance when
-multiple disks are used and each disk has its own storage controller.
-Note that backups do not currently work with *IO Thread* enabled.
-
+{pve} guide), you can activate the *Discard* option on a drive. With *Discard*
+set and a _TRIM_-enabled guest OS footnote:[TRIM, UNMAP, and discard
+https://en.wikipedia.org/wiki/Trim_%28computing%29], when the VM's filesystem
+marks blocks as unused after deleting files, the controller will relay this
+information to the storage, which will then shrink the disk image accordingly.
+For the guest to be able to issue _TRIM_ commands, you must enable the *Discard*
+option on the drive. Some guest operating systems may also require the
+*SSD Emulation* flag to be set. Note that *Discard* on *VirtIO Block* drives is
+only supported on guests using Linux Kernel 5.0 or higher.
+
+If you would like a drive to be presented to the guest as a solid-state drive
+rather than a rotational hard disk, you can set the *SSD emulation* option on
+that drive. There is no requirement that the underlying storage actually be
+backed by SSDs; this feature can be used with physical media of any type.
+Note that *SSD emulation* is not supported on *VirtIO Block* drives.
+
+
+[[qm_hard_disk_iothread]]
+IO Thread
+^^^^^^^^^
+The option *IO Thread* can only be used when using a disk with the *VirtIO*
+controller, or with the *SCSI* controller, when the emulated controller type is
+*VirtIO SCSI single*. With *IO Thread* enabled, QEMU creates one I/O thread per
+storage controller rather than handling all I/O in the main event loop or vCPU
+threads. One benefit is better work distribution and utilization of the
+underlying storage. Another benefit is reduced latency (hangs) in the guest for
+very I/O-intensive host workloads, since neither the main thread nor a vCPU
+thread can be blocked by disk I/O.
[[qm_cpu]]
CPU
~~~
-[thumbnail="gui-create-vm-cpu.png"]
+[thumbnail="screenshot/gui-create-vm-cpu.png"]
A *CPU socket* is a physical slot on a PC motherboard where you can plug a CPU.
This CPU can then contain one or many *cores*, which are independent
in that case it makes sense to set the number of sockets to what the license
allows you.
-Increasing the number of virtual cpus (cores and sockets) will usually provide a
+Increasing the number of virtual CPUs (cores and sockets) will usually provide a
performance improvement though that is heavily dependent on the use of the VM.
-Multithreaded applications will of course benefit from a large number of
-virtual cpus, as for each virtual cpu you add, Qemu will create a new thread of
+Multi-threaded applications will of course benefit from a large number of
+virtual CPUs, as for each virtual cpu you add, QEMU will create a new thread of
execution on the host system. If you're not sure about the workload of your VM,
it is usually a safe bet to set the number of *Total cores* to 2.
NOTE: It is perfectly safe if the _overall_ number of cores of all your VMs
-is greater than the number of cores on the server (e.g., 4 VMs with each 4
-cores on a machine with only 8 cores). In that case the host system will
-balance the Qemu execution threads between your server cores, just like if you
-were running a standard multithreaded application. However, {pve} will prevent
-you from assigning more virtual CPU cores than physically available, as this will
-only bring the performance down due to the cost of context switches.
+is greater than the number of cores on the server (for example, 4 VMs each with
+4 cores (= total 16) on a machine with only 8 cores). In that case the host
+system will balance the QEMU execution threads between your server cores, just
+like if you were running a standard multi-threaded application. However, {pve}
+will prevent you from starting VMs with more virtual CPU cores than physically
+available, as this will only bring the performance down due to the cost of
+context switches.
[[qm_cpu_resource_limits]]
Resource Limits
^^^^^^^^^^^^^^^
-In addition to the number of virtual cores, you can configure how much resources
-a VM can get in relation to the host CPU time and also in relation to other
-VMs.
-With the *cpulimit* (`Host CPU Time') option you can limit how much CPU time the
-whole VM can use on the host. It is a floating point value representing CPU
-time in percent, so `1.0` is equal to `100%`, `2.5` to `250%` and so on. If a
-single process would fully use one single core it would have `100%` CPU Time
-usage. If a VM with four cores utilizes all its cores fully it would
-theoretically use `400%`. In reality the usage may be even a bit higher as Qemu
-can have additional threads for VM peripherals besides the vCPU core ones.
-This setting can be useful if a VM should have multiple vCPUs, as it runs a few
-processes in parallel, but the VM as a whole should not be able to run all
-vCPUs at 100% at the same time. Using a specific example: lets say we have a VM
-which would profit from having 8 vCPUs, but at no time all of those 8 cores
-should run at full load - as this would make the server so overloaded that
-other VMs and CTs would get to less CPU. So, we set the *cpulimit* limit to
-`4.0` (=400%). If all cores do the same heavy work they would all get 50% of a
-real host cores CPU time. But, if only 4 would do work they could still get
-almost 100% of a real core each.
-
-NOTE: VMs can, depending on their configuration, use additional threads e.g.,
-for networking or IO operations but also live migration. Thus a VM can show up
-to use more CPU time than just its virtual CPUs could use. To ensure that a VM
-never uses more CPU time than virtual CPUs assigned set the *cpulimit* setting
-to the same value as the total core count.
-
-The second CPU resource limiting setting, *cpuunits* (nowadays often called CPU
-shares or CPU weight), controls how much CPU time a VM gets in regards to other
-VMs running. It is a relative weight which defaults to `1024`, if you increase
-this for a VM it will be prioritized by the scheduler in comparison to other
-VMs with lower weight. E.g., if VM 100 has set the default 1024 and VM 200 was
-changed to `2048`, the latter VM 200 would receive twice the CPU bandwidth than
-the first VM 100.
+*cpulimit*
+
+In addition to the number of virtual cores, the total available ``Host CPU
+Time'' for the VM can be set with the *cpulimit* option. It is a floating point
+value representing CPU time in percent, so `1.0` is equal to `100%`, `2.5` to
+`250%` and so on. If a single process would fully use one single core it would
+have `100%` CPU Time usage. If a VM with four cores utilizes all its cores
+fully it would theoretically use `400%`. In reality the usage may be even a bit
+higher as QEMU can have additional threads for VM peripherals besides the vCPU
+core ones.
+
+This setting can be useful when a VM should have multiple vCPUs because it is
+running some processes in parallel, but the VM as a whole should not be able to
+run all vCPUs at 100% at the same time.
+
+For example, suppose you have a virtual machine that would benefit from having 8
+virtual CPUs, but you don't want the VM to be able to max out all 8 cores
+running at full load - because that would overload the server and leave other
+virtual machines and containers with too little CPU time. To solve this, you
+could set *cpulimit* to `4.0` (=400%). This means that if the VM fully utilizes
+all 8 virtual CPUs by running 8 processes simultaneously, each vCPU will receive
+a maximum of 50% CPU time from the physical cores. However, if the VM workload
+only fully utilizes 4 virtual CPUs, it could still receive up to 100% CPU time
+from a physical core, for a total of 400%.
+
+NOTE: VMs can, depending on their configuration, use additional threads, such
+as for networking or IO operations but also live migration. Thus a VM can show
+up to use more CPU time than just its virtual CPUs could use. To ensure that a
+VM never uses more CPU time than vCPUs assigned, set the *cpulimit* to
+the same value as the total core count.
+
+*cpuuntis*
+
+With the *cpuunits* option, nowadays often called CPU shares or CPU weight, you
+can control how much CPU time a VM gets compared to other running VMs. It is a
+relative weight which defaults to `100` (or `1024` if the host uses legacy
+cgroup v1). If you increase this for a VM it will be prioritized by the
+scheduler in comparison to other VMs with lower weight.
+
+For example, if VM 100 has set the default `100` and VM 200 was changed to
+`200`, the latter VM 200 would receive twice the CPU bandwidth than the first
+VM 100.
For more information see `man systemd.resource-control`, here `CPUQuota`
-corresponds to `cpulimit` and `CPUShares` corresponds to our `cpuunits`
-setting, visit its Notes section for references and implementation details.
+corresponds to `cpulimit` and `CPUWeight` to our `cpuunits` setting. Visit its
+Notes section for references and implementation details.
+
+*affinity*
+
+With the *affinity* option, you can specify the physical CPU cores that are used
+to run the VM's vCPUs. Peripheral VM processes, such as those for I/O, are not
+affected by this setting. Note that the *CPU affinity is not a security
+feature*.
+
+Forcing a CPU *affinity* can make sense in certain cases but is accompanied by
+an increase in complexity and maintenance effort. For example, if you want to
+add more VMs later or migrate VMs to nodes with fewer CPU cores. It can also
+easily lead to asynchronous and therefore limited system performance if some
+CPUs are fully utilized while others are almost idle.
+
+The *affinity* is set through the `taskset` CLI tool. It accepts the host CPU
+numbers (see `lscpu`) in the `List Format` from `man cpuset`. This ASCII decimal
+list can contain numbers but also number ranges. For example, the *affinity*
+`0-1,8-11` (expanded `0, 1, 8, 9, 10, 11`) would allow the VM to run on only
+these six specific host cores.
CPU Type
^^^^^^^^
-Qemu can emulate a number different of *CPU types* from 486 to the latest Xeon
+QEMU can emulate a number different of *CPU types* from 486 to the latest Xeon
processors. Each new processor generation adds new features, like hardware
-assisted 3d rendering, random number generation, memory protection, etc ...
+assisted 3d rendering, random number generation, memory protection, etc. Also,
+a current generation can be upgraded through
+xref:chapter_firmware_updates[microcode update] with bug or security fixes.
+
Usually you should select for your VM a processor type which closely matches the
CPU of the host system, as it means that the host CPU features (also called _CPU
flags_ ) will be available in your VMs. If you want an exact match, you can set
as your host system.
This has a downside though. If you want to do a live migration of VMs between
-different hosts, your VM might end up on a new system with a different CPU type.
-If the CPU flags passed to the guest are missing, the qemu process will stop. To
-remedy this Qemu has also its own CPU type *kvm64*, that {pve} uses by defaults.
-kvm64 is a Pentium 4 look a like CPU type, which has a reduced CPU flags set,
-but is guaranteed to work everywhere.
+different hosts, your VM might end up on a new system with a different CPU type
+or a different microcode version.
+If the CPU flags passed to the guest are missing, the QEMU process will stop. To
+remedy this QEMU has also its own virtual CPU types, that {pve} uses by default.
+
+The backend default is 'kvm64' which works on essentially all x86_64 host CPUs
+and the UI default when creating a new VM is 'x86-64-v2-AES', which requires a
+host CPU starting from Westmere for Intel or at least a fourth generation
+Opteron for AMD.
+
+In short:
+
+If you don’t care about live migration or have a homogeneous cluster where all
+nodes have the same CPU and same microcode version, set the CPU type to host, as
+in theory this will give your guests maximum performance.
+
+If you care about live migration and security, and you have only Intel CPUs or
+only AMD CPUs, choose the lowest generation CPU model of your cluster.
+
+If you care about live migration without security, or have mixed Intel/AMD
+cluster, choose the lowest compatible virtual QEMU CPU type.
+
+NOTE: Live migrations between Intel and AMD host CPUs have no guarantee to work.
+
+See also
+xref:chapter_qm_vcpu_list[List of AMD and Intel CPU Types as Defined in QEMU].
+
+QEMU CPU Types
+^^^^^^^^^^^^^^
+
+QEMU also provide virtual CPU types, compatible with both Intel and AMD host
+CPUs.
+
+NOTE: To mitigate the Spectre vulnerability for virtual CPU types, you need to
+add the relevant CPU flags, see
+xref:qm_meltdown_spectre[Meltdown / Spectre related CPU flags].
+
+Historically, {pve} had the 'kvm64' CPU model, with CPU flags at the level of
+Pentium 4 enabled, so performance was not great for certain workloads.
+
+In the summer of 2020, AMD, Intel, Red Hat, and SUSE collaborated to define
+three x86-64 microarchitecture levels on top of the x86-64 baseline, with modern
+flags enabled. For details, see the
+https://gitlab.com/x86-psABIs/x86-64-ABI[x86-64-ABI specification].
+
+NOTE: Some newer distributions like CentOS 9 are now built with 'x86-64-v2'
+flags as a minimum requirement.
+
+* 'kvm64 (x86-64-v1)': Compatible with Intel CPU >= Pentium 4, AMD CPU >=
+Phenom.
++
+* 'x86-64-v2': Compatible with Intel CPU >= Nehalem, AMD CPU >= Opteron_G3.
+Added CPU flags compared to 'x86-64-v1': '+cx16', '+lahf-lm', '+popcnt', '+pni',
+'+sse4.1', '+sse4.2', '+ssse3'.
++
+* 'x86-64-v2-AES': Compatible with Intel CPU >= Westmere, AMD CPU >= Opteron_G4.
+Added CPU flags compared to 'x86-64-v2': '+aes'.
++
+* 'x86-64-v3': Compatible with Intel CPU >= Broadwell, AMD CPU >= EPYC. Added
+CPU flags compared to 'x86-64-v2-AES': '+avx', '+avx2', '+bmi1', '+bmi2',
+'+f16c', '+fma', '+movbe', '+xsave'.
++
+* 'x86-64-v4': Compatible with Intel CPU >= Skylake, AMD CPU >= EPYC v4 Genoa.
+Added CPU flags compared to 'x86-64-v3': '+avx512f', '+avx512bw', '+avx512cd',
+'+avx512dq', '+avx512vl'.
+
+Custom CPU Types
+^^^^^^^^^^^^^^^^
+
+You can specify custom CPU types with a configurable set of features. These are
+maintained in the configuration file `/etc/pve/virtual-guest/cpu-models.conf` by
+an administrator. See `man cpu-models.conf` for format details.
+
+Specified custom types can be selected by any user with the `Sys.Audit`
+privilege on `/nodes`. When configuring a custom CPU type for a VM via the CLI
+or API, the name needs to be prefixed with 'custom-'.
+
+[[qm_meltdown_spectre]]
+Meltdown / Spectre related CPU flags
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+There are several CPU flags related to the Meltdown and Spectre vulnerabilities
+footnote:[Meltdown Attack https://meltdownattack.com/] which need to be set
+manually unless the selected CPU type of your VM already enables them by default.
+
+There are two requirements that need to be fulfilled in order to use these
+CPU flags:
+
+* The host CPU(s) must support the feature and propagate it to the guest's virtual CPU(s)
+* The guest operating system must be updated to a version which mitigates the
+ attacks and is able to utilize the CPU feature
+
+Otherwise you need to set the desired CPU flag of the virtual CPU, either by
+editing the CPU options in the web UI, or by setting the 'flags' property of the
+'cpu' option in the VM configuration file.
+
+For Spectre v1,v2,v4 fixes, your CPU or system vendor also needs to provide a
+so-called ``microcode update'' for your CPU, see
+xref:chapter_firmware_updates[chapter Firmware Updates]. Note that not all
+affected CPUs can be updated to support spec-ctrl.
+
+
+To check if the {pve} host is vulnerable, execute the following command as root:
+
+----
+for f in /sys/devices/system/cpu/vulnerabilities/*; do echo "${f##*/} -" $(cat "$f"); done
+----
+
+A community script is also available to detect if the host is still vulnerable.
+footnote:[spectre-meltdown-checker https://meltdown.ovh/]
+
+Intel processors
+^^^^^^^^^^^^^^^^
+
+* 'pcid'
++
+This reduces the performance impact of the Meltdown (CVE-2017-5754) mitigation
+called 'Kernel Page-Table Isolation (KPTI)', which effectively hides
+the Kernel memory from the user space. Without PCID, KPTI is quite an expensive
+mechanism footnote:[PCID is now a critical performance/security feature on x86
+https://groups.google.com/forum/m/#!topic/mechanical-sympathy/L9mHTbeQLNU].
++
+To check if the {pve} host supports PCID, execute the following command as root:
++
+----
+# grep ' pcid ' /proc/cpuinfo
+----
++
+If this does not return empty your host's CPU has support for 'pcid'.
+
+* 'spec-ctrl'
++
+Required to enable the Spectre v1 (CVE-2017-5753) and Spectre v2 (CVE-2017-5715) fix,
+in cases where retpolines are not sufficient.
+Included by default in Intel CPU models with -IBRS suffix.
+Must be explicitly turned on for Intel CPU models without -IBRS suffix.
+Requires an updated host CPU microcode (intel-microcode >= 20180425).
++
+* 'ssbd'
++
+Required to enable the Spectre V4 (CVE-2018-3639) fix. Not included by default in any Intel CPU model.
+Must be explicitly turned on for all Intel CPU models.
+Requires an updated host CPU microcode(intel-microcode >= 20180703).
+
+
+AMD processors
+^^^^^^^^^^^^^^
+
+* 'ibpb'
++
+Required to enable the Spectre v1 (CVE-2017-5753) and Spectre v2 (CVE-2017-5715) fix,
+in cases where retpolines are not sufficient.
+Included by default in AMD CPU models with -IBPB suffix.
+Must be explicitly turned on for AMD CPU models without -IBPB suffix.
+Requires the host CPU microcode to support this feature before it can be used for guest CPUs.
+
+
+
+* 'virt-ssbd'
++
+Required to enable the Spectre v4 (CVE-2018-3639) fix.
+Not included by default in any AMD CPU model.
+Must be explicitly turned on for all AMD CPU models.
+This should be provided to guests, even if amd-ssbd is also provided, for maximum guest compatibility.
+Note that this must be explicitly enabled when when using the "host" cpu model,
+because this is a virtual feature which does not exist in the physical CPUs.
+
+
+* 'amd-ssbd'
++
+Required to enable the Spectre v4 (CVE-2018-3639) fix.
+Not included by default in any AMD CPU model. Must be explicitly turned on for all AMD CPU models.
+This provides higher performance than virt-ssbd, therefore a host supporting this should always expose this to guests if possible.
+virt-ssbd should none the less also be exposed for maximum guest compatibility as some kernels only know about virt-ssbd.
+
+
+* 'amd-no-ssb'
++
+Recommended to indicate the host is not vulnerable to Spectre V4 (CVE-2018-3639).
+Not included by default in any AMD CPU model.
+Future hardware generations of CPU will not be vulnerable to CVE-2018-3639,
+and thus the guest should be told not to enable its mitigations, by exposing amd-no-ssb.
+This is mutually exclusive with virt-ssbd and amd-ssbd.
-In short, if you care about live migration and moving VMs between nodes, leave
-the kvm64 default. If you don’t care about live migration or have a homogeneous
-cluster where all nodes have the same CPU, set the CPU type to host, as in
-theory this will give your guests maximum performance.
NUMA
^^^^
This option is also required to hot-plug cores or RAM in a VM.
If the NUMA option is used, it is recommended to set the number of sockets to
-the number of sockets of the host system.
+the number of nodes of the host system.
vCPU hot-plug
^^^^^^^^^^^^^
Modern operating systems introduced the capability to hot-plug and, to a
-certain extent, hot-unplug CPUs in a running systems. Virtualisation allows us
+certain extent, hot-unplug CPUs in a running system. Virtualization allows us
to avoid a lot of the (physical) problems real hardware can cause in such
scenarios.
Still, this is a rather new and complicated feature, so its use should be
In {pve} the maximal number of plugged CPUs is always `cores * sockets`.
To start a VM with less than this total core count of CPUs you may use the
-*vpus* setting, it denotes how many vCPUs should be plugged in at VM start.
+*vcpus* setting, it denotes how many vCPUs should be plugged in at VM start.
Currently only this feature is only supported on Linux, a kernel newer than 3.10
is needed, a kernel newer than 4.7 is recommended.
Save this under /etc/udev/rules.d/ as a file ending in `.rules`.
-Note: CPU hot-remove is machine dependent and requires guest cooperation.
-The deletion command does not guarantee CPU removal to actually happen,
-typically it's a request forwarded to guest using target dependent mechanism,
-e.g., ACPI on x86/amd64.
+Note: CPU hot-remove is machine dependent and requires guest cooperation. The
+deletion command does not guarantee CPU removal to actually happen, typically
+it's a request forwarded to guest OS using target dependent mechanism, such as
+ACPI on x86/amd64.
[[qm_memory]]
host.
.Fixed Memory Allocation
-[thumbnail="gui-create-vm-memory-fixed.png"]
+[thumbnail="screenshot/gui-create-vm-memory.png"]
-When choosing a *fixed size memory* {pve} will simply allocate what you
-specify to your VM.
+When setting memory and minimum memory to the same amount
+{pve} will simply allocate what you specify to your VM.
Even when using a fixed memory size, the ballooning device gets added to the
VM, because it delivers useful information such as how much memory the guest
really uses.
In general, you should leave *ballooning* enabled, but if you want to disable
-it (e.g. for debugging purposes), simply uncheck
-*Ballooning* or set
+it (like for debugging purposes), simply uncheck *Ballooning Device* or set
balloon: 0
in the configuration.
.Automatic Memory Allocation
-[thumbnail="gui-create-vm-memory-dynamic.png", float="left"]
// see autoballoon() in pvestatd.pm
-When choosing to *automatically allocate memory*, {pve} will make sure that the
+When setting the minimum memory lower than memory, {pve} will make sure that the
minimum amount you specified is always available to the VM, and if RAM usage on
the host is below 80%, will dynamically add memory to the guest up to the
maximum memory specified.
-When the host is becoming short on RAM, the VM will then release some memory
+When the host is running low on RAM, the VM will then release some memory
back to the host, swapping running processes if needed and starting the oom
killer in last resort. The passing around of memory between host and guest is
done via a special `balloon` kernel driver running inside the guest, which will
When multiple VMs use the autoallocate facility, it is possible to set a
*Shares* coefficient which indicates the relative amount of the free host memory
that each VM should take. Suppose for instance you have four VMs, three of them
-running a HTTP server and the last one is a database server. To cache more
+running an HTTP server and the last one is a database server. To cache more
database blocks in the database server RAM, you would like to prioritize the
database VM when spare RAM is available. For this you assign a Shares property
of 3000 to the database VM, leaving the other VMs to the Shares default setting
of 1000. The host server has 32GB of RAM, and is currently using 16GB, leaving 32
-* 80/100 - 16 = 9GB RAM to be allocated to the VMs. The database VM will get 9 *
-3000 / (3000 + 1000 + 1000 + 1000) = 4.5 GB extra RAM and each HTTP server will
-get 1/5 GB.
+* 80/100 - 16 = 9GB RAM to be allocated to the VMs on top of their configured
+minimum memory amount. The database VM will benefit from 9 * 3000 / (3000 +
+1000 + 1000 + 1000) = 4.5 GB extra RAM and each HTTP server from 1.5 GB.
All Linux distributions released after 2010 have the balloon kernel driver
included. For Windows OSes, the balloon driver needs to be added manually and can
Network Device
~~~~~~~~~~~~~~
-[thumbnail="gui-create-vm-network.png"]
+[thumbnail="screenshot/gui-create-vm-network.png"]
Each VM can have many _Network interface controllers_ (NIC), of four different
types:
tap device is added to a bridge, by default vmbr0 in {pve}. In this mode, VMs
have direct access to the Ethernet LAN on which the host is located.
* in the alternative *NAT mode*, each virtual NIC will only communicate with
-the Qemu user networking stack, where a built-in router and DHCP server can
+the QEMU user networking stack, where a built-in router and DHCP server can
provide network access. This built-in DHCP will serve addresses in the private
10.0.2.0/24 range. The NAT mode is much slower than the bridged mode, and
-should only be used for testing.
+should only be used for testing. This mode is only available via CLI or the API,
+but not via the web UI.
You can also skip adding a network device when creating a VM by selecting *No
network device*.
+You can overwrite the *MTU* setting for each VM network device. The option
+`mtu=1` represents a special case, in which the MTU value will be inherited
+from the underlying bridge.
+This option is only available for *VirtIO* network devices.
+
.Multiqueue
If you are using the VirtIO driver, you can optionally activate the
*Multiqueue* option. This option allows the guest OS to process networking
//http://blog.vmsplice.net/2011/09/qemu-internals-vhost-architecture.html
When using the VirtIO driver with {pve}, each NIC network queue is passed to the
-host kernel, where the queue will be processed by a kernel thread spawn by the
+host kernel, where the queue will be processed by a kernel thread spawned by the
vhost driver. With this option activated, it is possible to pass _multiple_
network queues to the host kernel for each NIC.
//https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Virtualization_Tuning_and_Optimization_Guide/sect-Virtualization_Tuning_Optimization_Guide-Networking-Techniques.html#sect-Virtualization_Tuning_Optimization_Guide-Networking-Multi-queue_virtio-net
-When using Multiqueue, it is recommended to set it to a value equal
-to the number of Total Cores of your guest. You also need to set in
-the VM the number of multi-purpose channels on each VirtIO NIC with the ethtool
-command:
+When using Multiqueue, it is recommended to set it to a value equal to the
+number of vCPUs of your guest. Remember that the number of vCPUs is the number
+of sockets times the number of cores configured for the VM. You also need to set
+the number of multi-purpose channels on each VirtIO NIC in the VM with this
+ethtool command:
`ethtool -L ens1 combined X`
-where X is the number of the number of vcpus of the VM.
+where X is the number of the number of vCPUs of the VM.
+
+To configure a Windows guest for Multiqueue install the
+https://pve.proxmox.com/wiki/Windows_VirtIO_Drivers[Redhat VirtIO Ethernet
+Adapter drivers], then adapt the NIC's configuration as follows. Open the
+device manager, right click the NIC under "Network adapters", and select
+"Properties". Then open the "Advanced" tab and select "Receive Side Scaling"
+from the list on the left. Make sure it is set to "Enabled". Next, navigate to
+"Maximum number of RSS Queues" in the list and set it to the number of vCPUs of
+your VM. Once you verified that the settings are correct, click "OK" to confirm
+them.
You should note that setting the Multiqueue parameter to a value greater
than one will increase the CPU load on the host and guest systems as the
process a great number of incoming connections, such as when the VM is running
as a router, reverse proxy or a busy HTTP server doing long polling.
+[[qm_display]]
+Display
+~~~~~~~
+
+QEMU can virtualize a few types of VGA hardware. Some examples are:
+
+* *std*, the default, emulates a card with Bochs VBE extensions.
+* *cirrus*, this was once the default, it emulates a very old hardware module
+with all its problems. This display type should only be used if really
+necessary footnote:[https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/
+qemu: using cirrus considered harmful], for example, if using Windows XP or
+earlier
+* *vmware*, is a VMWare SVGA-II compatible adapter.
+* *qxl*, is the QXL paravirtualized graphics card. Selecting this also
+enables https://www.spice-space.org/[SPICE] (a remote viewer protocol) for the
+VM.
+* *virtio-gl*, often named VirGL is a virtual 3D GPU for use inside VMs that
+ can offload workloads to the host GPU without requiring special (expensive)
+ models and drivers and neither binding the host GPU completely, allowing
+ reuse between multiple guests and or the host.
++
+NOTE: VirGL support needs some extra libraries that aren't installed by
+default due to being relatively big and also not available as open source for
+all GPU models/vendors. For most setups you'll just need to do:
+`apt install libgl1 libegl1`
+
+You can edit the amount of memory given to the virtual GPU, by setting
+the 'memory' option. This can enable higher resolutions inside the VM,
+especially with SPICE/QXL.
+
+As the memory is reserved by display device, selecting Multi-Monitor mode
+for SPICE (such as `qxl2` for dual monitors) has some implications:
+
+* Windows needs a device for each monitor, so if your 'ostype' is some
+version of Windows, {pve} gives the VM an extra device per monitor.
+Each device gets the specified amount of memory.
+
+* Linux VMs, can always enable more virtual monitors, but selecting
+a Multi-Monitor mode multiplies the memory given to the device with
+the number of monitors.
+
+Selecting `serialX` as display 'type' disables the VGA output, and redirects
+the Web Console to the selected serial port. A configured display 'memory'
+setting will be ignored in that case.
+
+.VNC clipboard
+You can enable the VNC clipboard by setting `clipboard` to `vnc`.
+
+----
+# qm set <vmid> -vga <displaytype>,clipboard=vnc
+----
+
+In order to use the clipboard feature, you must first install the
+SPICE guest tools. On Debian-based distributions, this can be achieved
+by installing `spice-vdagent`. For other Operating Systems search for it
+in the offical repositories or see: https://www.spice-space.org/download.html
+
+Once you have installed the spice guest tools, you can use the VNC clipboard
+function (e.g. in the noVNC console panel). However, if you're using
+SPICE, virtio or virgl, you'll need to choose which clipboard to use.
+This is because the default *SPICE* clipboard will be replaced by the
+*VNC* clipboard, if `clipboard` is set to `vnc`.
[[qm_usb_passthrough]]
USB Passthrough
a VM online to another host, since the hardware is only available
on the host the VM is currently residing.
-The second type of passthrough is SPICE USB passthrough. This is useful
-if you use a SPICE client which supports it. If you add a SPICE USB port
-to your VM, you can passthrough a USB device from where your SPICE client is,
-directly to the VM (for example an input device or hardware dongle).
+The second type of passthrough is SPICE USB passthrough. If you add one or more
+SPICE USB ports to your VM, you can dynamically pass a local USB device from
+your SPICE client through to the VM. This can be useful to redirect an input
+device or hardware dongle temporarily.
+It is also possible to map devices on a cluster level, so that they can be
+properly used with HA and hardware changes are detected and non root users
+can configure them. See xref:resource_mapping[Resource Mapping]
+for details on that.
[[qm_bios_and_uefi]]
BIOS and UEFI
~~~~~~~~~~~~~
In order to properly emulate a computer, QEMU needs to use a firmware.
-By default QEMU uses *SeaBIOS* for this, which is an open-source, x86 BIOS
-implementation. SeaBIOS is a good choice for most standard setups.
-
-There are, however, some scenarios in which a BIOS is not a good firmware
-to boot from, e.g. if you want to do VGA passthrough. footnote:[Alex Williamson has a very good blog entry about this.
-http://vfio.blogspot.co.at/2014/08/primary-graphics-assignment-without-vga.html]
-In such cases, you should rather use *OVMF*, which is an open-source UEFI implementation. footnote:[See the OVMF Project http://www.tianocore.org/ovmf/]
+Which, on common PCs often known as BIOS or (U)EFI, is executed as one of the
+first steps when booting a VM. It is responsible for doing basic hardware
+initialization and for providing an interface to the firmware and hardware for
+the operating system. By default QEMU uses *SeaBIOS* for this, which is an
+open-source, x86 BIOS implementation. SeaBIOS is a good choice for most
+standard setups.
+
+Some operating systems (such as Windows 11) may require use of an UEFI
+compatible implementation. In such cases, you must use *OVMF* instead,
+which is an open-source UEFI implementation. footnote:[See the OVMF Project https://github.com/tianocore/tianocore.github.io/wiki/OVMF]
+
+There are other scenarios in which the SeaBIOS may not be the ideal firmware to
+boot from, for example if you want to do VGA passthrough. footnote:[Alex
+Williamson has a good blog entry about this
+https://vfio.blogspot.co.at/2014/08/primary-graphics-assignment-without-vga.html]
If you want to use OVMF, there are several things to consider:
You can create such a disk with the following command:
- qm set <vmid> -efidisk0 <storage>:1,format=<format>
+----
+# qm set <vmid> -efidisk0 <storage>:1,format=<format>,efitype=4m,pre-enrolled-keys=1
+----
Where *<storage>* is the storage where you want to have the disk, and
*<format>* is a format which the storage supports. Alternatively, you can
create such a disk through the web interface with 'Add' -> 'EFI Disk' in the
hardware section of a VM.
+The *efitype* option specifies which version of the OVMF firmware should be
+used. For new VMs, this should always be '4m', as it supports Secure Boot and
+has more space allocated to support future development (this is the default in
+the GUI).
+
+*pre-enroll-keys* specifies if the efidisk should come pre-loaded with
+distribution-specific and Microsoft Standard Secure Boot keys. It also enables
+Secure Boot by default (though it can still be disabled in the OVMF menu within
+the VM).
+
+NOTE: If you want to start using Secure Boot in an existing VM (that still uses
+a '2m' efidisk), you need to recreate the efidisk. To do so, delete the old one
+(`qm set <vmid> -delete efidisk0`) and add a new one as described above. This
+will reset any custom configurations you have made in the OVMF menu!
+
When using OVMF with a virtual display (without VGA passthrough),
-you need to set the client resolution in the OVMF menu(which you can reach
+you need to set the client resolution in the OVMF menu (which you can reach
with a press of the ESC button during boot), or you have to choose
SPICE as the display type.
+[[qm_tpm]]
+Trusted Platform Module (TPM)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A *Trusted Platform Module* is a device which stores secret data - such as
+encryption keys - securely and provides tamper-resistance functions for
+validating system boot.
+
+Certain operating systems (such as Windows 11) require such a device to be
+attached to a machine (be it physical or virtual).
+
+A TPM is added by specifying a *tpmstate* volume. This works similar to an
+efidisk, in that it cannot be changed (only removed) once created. You can add
+one via the following command:
+
+----
+# qm set <vmid> -tpmstate0 <storage>:1,version=<version>
+----
+
+Where *<storage>* is the storage you want to put the state on, and *<version>*
+is either 'v1.2' or 'v2.0'. You can also add one via the web interface, by
+choosing 'Add' -> 'TPM State' in the hardware section of a VM.
+
+The 'v2.0' TPM spec is newer and better supported, so unless you have a specific
+implementation that requires a 'v1.2' TPM, it should be preferred.
+
+NOTE: Compared to a physical TPM, an emulated one does *not* provide any real
+security benefits. The point of a TPM is that the data on it cannot be modified
+easily, except via commands specified as part of the TPM spec. Since with an
+emulated device the data storage happens on a regular volume, it can potentially
+be edited by anyone with access to it.
+
+[[qm_ivshmem]]
+Inter-VM shared memory
+~~~~~~~~~~~~~~~~~~~~~~
+
+You can add an Inter-VM shared memory device (`ivshmem`), which allows one to
+share memory between the host and a guest, or also between multiple guests.
+
+To add such a device, you can use `qm`:
+
+----
+# qm set <vmid> -ivshmem size=32,name=foo
+----
+
+Where the size is in MiB. The file will be located under
+`/dev/shm/pve-shm-$name` (the default name is the vmid).
+
+NOTE: Currently the device will get deleted as soon as any VM using it got
+shutdown or stopped. Open connections will still persist, but new connections
+to the exact same device cannot be made anymore.
+
+A use case for such a device is the Looking Glass
+footnote:[Looking Glass: https://looking-glass.io/] project, which enables high
+performance, low-latency display mirroring between host and guest.
+
+[[qm_audio_device]]
+Audio Device
+~~~~~~~~~~~~
+
+To add an audio device run the following command:
+
+----
+qm set <vmid> -audio0 device=<device>
+----
+
+Supported audio devices are:
+
+* `ich9-intel-hda`: Intel HD Audio Controller, emulates ICH9
+* `intel-hda`: Intel HD Audio Controller, emulates ICH6
+* `AC97`: Audio Codec '97, useful for older operating systems like Windows XP
+
+There are two backends available:
+
+* 'spice'
+* 'none'
+
+The 'spice' backend can be used in combination with xref:qm_display[SPICE] while
+the 'none' backend can be useful if an audio device is needed in the VM for some
+software to work. To use the physical audio device of the host use device
+passthrough (see xref:qm_pci_passthrough[PCI Passthrough] and
+xref:qm_usb_passthrough[USB Passthrough]). Remote protocols like Microsoft’s RDP
+have options to play sound.
+
+
+[[qm_virtio_rng]]
+VirtIO RNG
+~~~~~~~~~~
+
+A RNG (Random Number Generator) is a device providing entropy ('randomness') to
+a system. A virtual hardware-RNG can be used to provide such entropy from the
+host system to a guest VM. This helps to avoid entropy starvation problems in
+the guest (a situation where not enough entropy is available and the system may
+slow down or run into problems), especially during the guests boot process.
+
+To add a VirtIO-based emulated RNG, run the following command:
+
+----
+qm set <vmid> -rng0 source=<source>[,max_bytes=X,period=Y]
+----
+
+`source` specifies where entropy is read from on the host and has to be one of
+the following:
+
+* `/dev/urandom`: Non-blocking kernel entropy pool (preferred)
+* `/dev/random`: Blocking kernel pool (not recommended, can lead to entropy
+ starvation on the host system)
+* `/dev/hwrng`: To pass through a hardware RNG attached to the host (if multiple
+ are available, the one selected in
+ `/sys/devices/virtual/misc/hw_random/rng_current` will be used)
+
+A limit can be specified via the `max_bytes` and `period` parameters, they are
+read as `max_bytes` per `period` in milliseconds. However, it does not represent
+a linear relationship: 1024B/1000ms would mean that up to 1 KiB of data becomes
+available on a 1 second timer, not that 1 KiB is streamed to the guest over the
+course of one second. Reducing the `period` can thus be used to inject entropy
+into the guest at a faster rate.
+
+By default, the limit is set to 1024 bytes per 1000 ms (1 KiB/s). It is
+recommended to always use a limiter to avoid guests using too many host
+resources. If desired, a value of '0' for `max_bytes` can be used to disable
+all limits.
+
+[[qm_bootorder]]
+Device Boot Order
+~~~~~~~~~~~~~~~~~
+
+QEMU can tell the guest which devices it should boot from, and in which order.
+This can be specified in the config via the `boot` property, for example:
+
+----
+boot: order=scsi0;net0;hostpci0
+----
+
+[thumbnail="screenshot/gui-qemu-edit-bootorder.png"]
+
+This way, the guest would first attempt to boot from the disk `scsi0`, if that
+fails, it would go on to attempt network boot from `net0`, and in case that
+fails too, finally attempt to boot from a passed through PCIe device (seen as
+disk in case of NVMe, otherwise tries to launch into an option ROM).
+
+On the GUI you can use a drag-and-drop editor to specify the boot order, and use
+the checkbox to enable or disable certain devices for booting altogether.
+
+NOTE: If your guest uses multiple disks to boot the OS or load the bootloader,
+all of them must be marked as 'bootable' (that is, they must have the checkbox
+enabled or appear in the list in the config) for the guest to be able to boot.
+This is because recent SeaBIOS and OVMF versions only initialize disks if they
+are marked 'bootable'.
+
+In any case, even devices not appearing in the list or having the checkmark
+disabled will still be available to the guest, once it's operating system has
+booted and initialized them. The 'bootable' flag only affects the guest BIOS and
+bootloader.
+
+
[[qm_startup_and_shutdown]]
Automatic Start and Shutdown of Virtual Machines
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
boot' from the 'Options' Tab of your VM in the web interface, or set it with
the following command:
- qm set <vmid> -onboot 1
+----
+# qm set <vmid> -onboot 1
+----
.Start and Shutdown Order
-[thumbnail="gui-qemu-edit-start-order.png"]
+[thumbnail="screenshot/gui-qemu-edit-start-order.png"]
In some case you want to be able to fine tune the boot order of your
VMs, for instance if one of your VM is providing firewalling or DHCP
to other guest systems. For this you can use the following
parameters:
-* *Start/Shutdown order*: Defines the start order priority. E.g. set it to 1 if
-you want the VM to be the first to be started. (We use the reverse startup
-order for shutdown, so a machine with a start order of 1 would be the last to
-be shut down)
+* *Start/Shutdown order*: Defines the start order priority. For example, set it
+to 1 if you want the VM to be the first to be started. (We use the reverse
+startup order for shutdown, so a machine with a start order of 1 would be the
+last to be shut down). If multiple VMs have the same order defined on a host,
+they will additionally be ordered by 'VMID' in ascending order.
* *Startup delay*: Defines the interval between this VM start and subsequent
-VMs starts . E.g. set it to 240 if you want to wait 240 seconds before starting
-other VMs.
+VMs starts. For example, set it to 240 if you want to wait 240 seconds before
+starting other VMs.
* *Shutdown timeout*: Defines the duration in seconds {pve} should wait
-for the VM to be offline after issuing a shutdown command.
-By default this value is set to 60, which means that {pve} will issue a
-shutdown request, wait 60s for the machine to be offline, and if after 60s
-the machine is still online will notify that the shutdown action failed.
+for the VM to be offline after issuing a shutdown command. By default this
+value is set to 180, which means that {pve} will issue a shutdown request and
+wait 180 seconds for the machine to be offline. If the machine is still online
+after the timeout it will be stopped forcefully.
NOTE: VMs managed by the HA stack do not follow the 'start on boot' and
'boot order' options currently. Those VMs will be skipped by the startup and
stopped.
Please note that machines without a Start/Shutdown order parameter will always
-start after those where the parameter is set, and this parameter only
-makes sense between the machines running locally on a host, and not
+start after those where the parameter is set. Further, this parameter can only
+be enforced between virtual machines running on the same host, not
cluster-wide.
+If you require a delay between the host boot and the booting of the first VM,
+see the section on xref:first_guest_boot_delay[Proxmox VE Node Management].
+
+
+[[qm_qemu_agent]]
+QEMU Guest Agent
+~~~~~~~~~~~~~~~~
+
+The QEMU Guest Agent is a service which runs inside the VM, providing a
+communication channel between the host and the guest. It is used to exchange
+information and allows the host to issue commands to the guest.
+
+For example, the IP addresses in the VM summary panel are fetched via the guest
+agent.
+
+Or when starting a backup, the guest is told via the guest agent to sync
+outstanding writes via the 'fs-freeze' and 'fs-thaw' commands.
+
+For the guest agent to work properly the following steps must be taken:
+
+* install the agent in the guest and make sure it is running
+* enable the communication via the agent in {pve}
+
+Install Guest Agent
+^^^^^^^^^^^^^^^^^^^
+
+For most Linux distributions, the guest agent is available. The package is
+usually named `qemu-guest-agent`.
+
+For Windows, it can be installed from the
+https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/virtio-win.iso[Fedora
+VirtIO driver ISO].
+
+[[qm_qga_enable]]
+Enable Guest Agent Communication
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Communication from {pve} with the guest agent can be enabled in the VM's
+*Options* panel. A fresh start of the VM is necessary for the changes to take
+effect.
+
+[[qm_qga_auto_trim]]
+Automatic TRIM Using QGA
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+It is possible to enable the 'Run guest-trim' option. With this enabled,
+{pve} will issue a trim command to the guest after the following
+operations that have the potential to write out zeros to the storage:
+
+* moving a disk to another storage
+* live migrating a VM to another node with local storage
+
+On a thin provisioned storage, this can help to free up unused space.
+
+NOTE: There is a caveat with ext4 on Linux, because it uses an in-memory
+optimization to avoid issuing duplicate TRIM requests. Since the guest doesn't
+know about the change in the underlying storage, only the first guest-trim will
+run as expected. Subsequent ones, until the next reboot, will only consider
+parts of the filesystem that changed since then.
+
+[[qm_qga_fsfreeze]]
+Filesystem Freeze & Thaw on Backup
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+By default, guest filesystems are synced via the 'fs-freeze' QEMU Guest Agent
+Command when a backup is performed, to provide consistency.
+
+On Windows guests, some applications might handle consistent backups themselves
+by hooking into the Windows VSS (Volume Shadow Copy Service) layer, a
+'fs-freeze' then might interfere with that. For example, it has been observed
+that calling 'fs-freeze' with some SQL Servers triggers VSS to call the SQL
+Writer VSS module in a mode that breaks the SQL Server backup chain for
+differential backups.
+
+For such setups you can configure {pve} to not issue a freeze-and-thaw cycle on
+backup by setting the `freeze-fs-on-backup` QGA option to `0`. This can also be
+done via the GUI with the 'Freeze/thaw guest filesystems on backup for
+consistency' option.
+
+IMPORTANT: Disabling this option can potentially lead to backups with inconsistent
+filesystems and should therefore only be disabled if you know what you are
+doing.
+
+Troubleshooting
+^^^^^^^^^^^^^^^
+
+.VM does not shut down
+
+Make sure the guest agent is installed and running.
+
+Once the guest agent is enabled, {pve} will send power commands like
+'shutdown' via the guest agent. If the guest agent is not running, commands
+cannot get executed properly and the shutdown command will run into a timeout.
+
+[[qm_spice_enhancements]]
+SPICE Enhancements
+~~~~~~~~~~~~~~~~~~
+
+SPICE Enhancements are optional features that can improve the remote viewer
+experience.
+
+To enable them via the GUI go to the *Options* panel of the virtual machine. Run
+the following command to enable them via the CLI:
+
+----
+qm set <vmid> -spice_enhancements foldersharing=1,videostreaming=all
+----
+
+NOTE: To use these features the <<qm_display,*Display*>> of the virtual machine
+must be set to SPICE (qxl).
+
+Folder Sharing
+^^^^^^^^^^^^^^
+
+Share a local folder with the guest. The `spice-webdavd` daemon needs to be
+installed in the guest. It makes the shared folder available through a local
+WebDAV server located at http://localhost:9843.
+
+For Windows guests the installer for the 'Spice WebDAV daemon' can be downloaded
+from the
+https://www.spice-space.org/download.html#windows-binaries[official SPICE website].
+
+Most Linux distributions have a package called `spice-webdavd` that can be
+installed.
+
+To share a folder in Virt-Viewer (Remote Viewer) go to 'File -> Preferences'.
+Select the folder to share and then enable the checkbox.
+
+NOTE: Folder sharing currently only works in the Linux version of Virt-Viewer.
+
+CAUTION: Experimental! Currently this feature does not work reliably.
+
+Video Streaming
+^^^^^^^^^^^^^^^
+
+Fast refreshing areas are encoded into a video stream. Two options exist:
+
+* *all*: Any fast refreshing area will be encoded into a video stream.
+* *filter*: Additional filters are used to decide if video streaming should be
+ used (currently only small window surfaces are skipped).
+
+A general recommendation if video streaming should be enabled and which option
+to choose from cannot be given. Your mileage may vary depending on the specific
+circumstances.
+
+Troubleshooting
+^^^^^^^^^^^^^^^
+
+.Shared folder does not show up
+
+Make sure the WebDAV service is enabled and running in the guest. On Windows it
+is called 'Spice webdav proxy'. In Linux the name is 'spice-webdavd' but can be
+different depending on the distribution.
+
+If the service is running, check the WebDAV server by opening
+http://localhost:9843 in a browser in the guest.
+
+It can help to restart the SPICE session.
[[qm_migration]]
Migration
---------
-[thumbnail="gui-qemu-migrate.png"]
+[thumbnail="screenshot/gui-qemu-migrate.png"]
If you have a cluster, you can migrate your VM to another host with
- qm migrate <vmid> <target>
+----
+# qm migrate <vmid> <target>
+----
There are generally two mechanisms for this
Online Migration
~~~~~~~~~~~~~~~~
-When your VM is running and it has no local resources defined (such as disks
-on local storage, passed through devices, etc.) you can initiate a live
-migration with the -online flag.
+If your VM is running and no locally bound resources are configured (such as
+devices that are passed through), you can initiate a live migration with the `--online`
+flag in the `qm migration` command evocation. The web interface defaults to
+live migration when the VM is running.
How it works
^^^^^^^^^^^^
-This starts a Qemu Process on the target host with the 'incoming' flag, which
-means that the process starts and waits for the memory data and device states
-from the source Virtual Machine (since all other resources, e.g. disks,
-are shared, the memory content and device state are the only things left
-to transmit).
-
-Once this connection is established, the source begins to send the memory
-content asynchronously to the target. If the memory on the source changes,
-those sections are marked dirty and there will be another pass of sending data.
-This happens until the amount of data to send is so small that it can
-pause the VM on the source, send the remaining data to the target and start
-the VM on the target in under a second.
+Online migration first starts a new QEMU process on the target host with the
+'incoming' flag, which performs only basic initialization with the guest vCPUs
+still paused and then waits for the guest memory and device state data streams
+of the source Virtual Machine.
+All other resources, such as disks, are either shared or got already sent
+before runtime state migration of the VMs begins; so only the memory content
+and device state remain to be transferred.
+
+Once this connection is established, the source begins asynchronously sending
+the memory content to the target. If the guest memory on the source changes,
+those sections are marked dirty and another pass is made to send the guest
+memory data.
+This loop is repeated until the data difference between running source VM
+and incoming target VM is small enough to be sent in a few milliseconds,
+because then the source VM can be paused completely, without a user or program
+noticing the pause, so that the remaining data can be sent to the target, and
+then unpause the targets VM's CPU to make it the new running VM in well under a
+second.
Requirements
^^^^^^^^^^^^
For Live Migration to work, there are some things required:
-* The VM has no local resources (e.g. passed through devices, local disks, etc.)
-* The hosts are in the same {pve} cluster.
-* The hosts have a working (and reliable) network connection.
-* The target host must have the same or higher versions of the
- {pve} packages. (It *might* work the other way, but this is never guaranteed)
+* The VM has no local resources that cannot be migrated. For example,
+ PCI or USB devices that are passed through currently block live-migration.
+ Local Disks, on the other hand, can be migrated by sending them to the target
+ just fine.
+* The hosts are located in the same {pve} cluster.
+* The hosts have a working (and reliable) network connection between them.
+* The target host must have the same, or higher versions of the
+ {pve} packages. Although it can sometimes work the other way around, this
+ cannot be guaranteed.
+* The hosts have CPUs from the same vendor with similar capabilities. Different
+ vendor *might* work depending on the actual models and VMs CPU type
+ configured, but it cannot be guaranteed - so please test before deploying
+ such a setup in production.
Offline Migration
~~~~~~~~~~~~~~~~~
-If you have local resources, you can still offline migrate your VMs,
-as long as all disk are on storages, which are defined on both hosts.
-Then the migration will copy the disk over the network to the target host.
+If you have local resources, you can still migrate your VMs offline as long as
+all disk are on storage defined on both hosts.
+Migration then copies the disks to the target host over the network, as with
+online migration. Note that any hardware passthrough configuration may need to
+be adapted to the device location on the target host.
+
+// TODO: mention hardware map IDs as better way to solve that, once available
[[qm_copy_and_clone]]
Copies and Clones
-----------------
-[thumbnail="gui-qemu-full-clone.png"]
+[thumbnail="screenshot/gui-qemu-full-clone.png"]
VM installation is usually done using an installation media (CD-ROM)
-from the operation system vendor. Depending on the OS, this can be a
+from the operating system vendor. Depending on the OS, this can be a
time consuming task one might want to avoid.
An easy way to deploy many VMs of the same type is to copy an existing
disk image *Format* if the storage driver supports several formats.
+
-NOTE: A full clone need to read and copy all VM image data. This is
+NOTE: A full clone needs to read and copy all VM image data. This is
usually much slower than creating a linked clone.
+
Linked Clone::
-Modern storage drivers supports a way to generate fast linked
+Modern storage drivers support a way to generate fast linked
clones. Such a clone is a writable copy whose initial contents are the
same as the original data. Creating a linked clone is nearly
instantaneous, and initially consumes no additional space.
templates can later be used to create linked clones efficiently.
+
-NOTE: You cannot delete the original template while linked clones
-exists.
+NOTE: You cannot delete an original template while linked clones
+exist.
+
It is not possible to change the *Target storage* for linked clones,
different node. The only restriction is that the VM is on shared
storage, and that storage is also available on the target node.
-To avoid resource conflicts, all network interface MAC addresses gets
+To avoid resource conflicts, all network interface MAC addresses get
randomized, and we generate a new 'UUID' for the VM BIOS (smbios1)
setting.
the disk images. If you want to change the template, create a linked
clone and modify that.
-Importing Virtual Machines and disk images
-------------------------------------------
+VM Generation ID
+----------------
+
+{pve} supports Virtual Machine Generation ID ('vmgenid') footnote:[Official
+'vmgenid' Specification
+https://docs.microsoft.com/en-us/windows/desktop/hyperv_v2/virtual-machine-generation-identifier]
+for virtual machines.
+This can be used by the guest operating system to detect any event resulting
+in a time shift event, for example, restoring a backup or a snapshot rollback.
+
+When creating new VMs, a 'vmgenid' will be automatically generated and saved
+in its configuration file.
+
+To create and add a 'vmgenid' to an already existing VM one can pass the
+special value `1' to let {pve} autogenerate one or manually set the 'UUID'
+footnote:[Online GUID generator http://guid.one/] by using it as value, for
+example:
+
+----
+# qm set VMID -vmgenid 1
+# qm set VMID -vmgenid 00000000-0000-0000-0000-000000000000
+----
+
+NOTE: The initial addition of a 'vmgenid' device to an existing VM, may result
+in the same effects as a change on snapshot rollback, backup restore, etc., has
+as the VM can interpret this as generation change.
+
+In the rare case the 'vmgenid' mechanism is not wanted one can pass `0' for
+its value on VM creation, or retroactively delete the property in the
+configuration with:
+
+----
+# qm set VMID -delete vmgenid
+----
+
+The most prominent use case for 'vmgenid' are newer Microsoft Windows
+operating systems, which use it to avoid problems in time sensitive or
+replicate services (such as databases or domain controller
+footnote:[https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/get-started/virtual-dc/virtualized-domain-controller-architecture])
+on snapshot rollback, backup restore or a whole VM clone operation.
+
+[[qm_import_virtual_machines]]
+Importing Virtual Machines
+--------------------------
+
+Importing existing virtual machines from foreign hypervisors or other {pve}
+clusters can be achieved through various methods, the most common ones are:
+
+* Using the native import wizard, which utilizes the 'import' content type, such
+ as provided by the ESXi special storage.
+* Performing a backup on the source and then restoring on the target. This
+ method works best when migrating from another {pve} instance.
+* using the OVF-specific import command of the `qm` command-line tool.
+
+If you import VMs to {pve} from other hypervisors, it’s recommended to
+familiarize yourself with the
+https://pve.proxmox.com/wiki/Migrate_to_Proxmox_VE#Concepts[concepts of {pve}].
+
+Import Wizard
+~~~~~~~~~~~~~
+
+[thumbnail="screenshot/gui-import-wizard-general.png"]
+
+{pve} provides an integrated VM importer using the storage plugin system for
+native integration into the API and web-based user interface. You can use this
+to import the VM as a whole, with most of its config mapped to {pve}'s config
+model and reduced downtime.
+
+NOTE: The import wizard was added during the {pve} 8.2 development cycle and is
+in tech preview state. While it's already promising and working stable, it's
+still under active development, focusing on adding other import-sources, like
+for example OVF/OVA files, in the future.
+
+To use the import wizard you have to first set up a new storage for an import
+source, you can do so on the web-interface under _Datacenter -> Storage -> Add_.
+
+Then you can select the new storage in the resource tree and use the 'Virtual
+Guests' content tab to see all available guests that can be imported.
+
+[thumbnail="screenshot/gui-import-wizard-advanced.png"]
+
+Select one and use the 'Import' button (or double-click) to open the import
+wizard. You can modify a subset of the available options here and then start the
+import. Please note that you can do more advanced modifications after the import
+finished.
+
+TIP: The import wizard is currently (2024-03) available for ESXi and has been
+tested with ESXi versions 6.5 through 8.0. Note that guests using vSAN storage
+cannot be directly imported directly; their disks must first be moved to another
+storage. While it is possible to use a vCenter as the import source, performance
+is dramatically degraded (5 to 10 times slower).
+
+For a step-by-step guide and tips for how to adapt the virtual guest to the new
+hyper-visor see our
+https://pve.proxmox.com/wiki/Migrate_to_Proxmox_VE#Migration[migrate to {pve}
+wiki article].
+
+Import OVF/OVA Through CLI
+~~~~~~~~~~~~~~~~~~~~~~~~~~
A VM export from a foreign hypervisor takes usually the form of one or more disk
images, with a configuration file describing the settings of the VM (RAM,
cases due to the problems above.
Step-by-step example of a Windows OVF import
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Microsoft provides
https://developer.microsoft.com/en-us/windows/downloads/virtual-machines/[Virtual Machines downloads]
- to get started with Windows development.We are going to use one of these
+ to get started with Windows development.We are going to use one of these
to demonstrate the OVF import feature.
Download the Virtual Machine zip
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+++++++++++++++++++++++++++++++++
-After getting informed about the user agreement, choose the _Windows 10
+After getting informed about the user agreement, choose the _Windows 10
Enterprise (Evaluation - Build)_ for the VMware platform, and download the zip.
Extract the disk image from the zip
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
++++++++++++++++++++++++++++++++++++
Using the `unzip` utility or any archiver of your choice, unpack the zip,
and copy via ssh/scp the ovf and vmdk files to your {pve} host.
Import the Virtual Machine
-^^^^^^^^^^^^^^^^^^^^^^^^^^
+++++++++++++++++++++++++++
This will create a new virtual machine, using cores, memory and
VM name as read from the OVF manifest, and import the disks to the +local-lvm+
storage. You have to configure the network manually.
- qm importovf 999 WinDev1709Eval.ovf local-lvm
+----
+# qm importovf 999 WinDev1709Eval.ovf local-lvm
+----
The VM is ready to be started.
Adding an external disk image to a Virtual Machine
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+++++++++++++++++++++++++++++++++++++++++++++++++++
-You can also add an existing disk image to a VM, either coming from a
+You can also add an existing disk image to a VM, either coming from a
foreign hypervisor, or one that you created yourself.
Suppose you created a Debian/Ubuntu disk image with the 'vmdebootstrap' tool:
--customize=./copy_pub_ssh.sh \
--sparse --image vm600.raw
-You can now create a new target VM for this image.
+You can now create a new target VM, importing the image to the storage `pvedir`
+and attaching it to the VM's SCSI controller:
- qm create 600 --net0 virtio,bridge=vmbr0 --name vm600 --serial0 socket \
- --bootdisk scsi0 --scsihw virtio-scsi-pci --ostype l26
+----
+# qm create 600 --net0 virtio,bridge=vmbr0 --name vm600 --serial0 socket \
+ --boot order=scsi0 --scsihw virtio-scsi-pci --ostype l26 \
+ --scsi0 pvedir:0,import-from=/path/to/dir/vm600.raw
+----
-Add the disk image as +unused0+ to the VM, using the storage +pvedir+:
+The VM is ready to be started.
- qm importdisk 600 vm600.raw pvedir
-Finally attach the unused disk to the SCSI controller of the VM:
+ifndef::wiki[]
+include::qm-cloud-init.adoc[]
+endif::wiki[]
- qm set 600 --scsi0 pvedir:600/vm-600-disk-1.raw
+ifndef::wiki[]
+include::qm-pci-passthrough.adoc[]
+endif::wiki[]
-The VM is ready to be started.
+Hookscripts
+-----------
+
+You can add a hook script to VMs with the config property `hookscript`.
+
+----
+# qm set 100 --hookscript local:snippets/hookscript.pl
+----
+
+It will be called during various phases of the guests lifetime.
+For an example and documentation see the example script under
+`/usr/share/pve-docs/examples/guest-example-hookscript.pl`.
+
+[[qm_hibernate]]
+Hibernation
+-----------
+
+You can suspend a VM to disk with the GUI option `Hibernate` or with
+
+----
+# qm suspend ID --todisk
+----
+
+That means that the current content of the memory will be saved onto disk
+and the VM gets stopped. On the next start, the memory content will be
+loaded and the VM can continue where it was left off.
+
+[[qm_vmstatestorage]]
+.State storage selection
+If no target storage for the memory is given, it will be automatically
+chosen, the first of:
+
+1. The storage `vmstatestorage` from the VM config.
+2. The first shared storage from any VM disk.
+3. The first non-shared storage from any VM disk.
+4. The storage `local` as a fallback.
+
+[[resource_mapping]]
+Resource Mapping
+----------------
+
+[thumbnail="screenshot/gui-datacenter-resource-mappings.png"]
+
+When using or referencing local resources (e.g. address of a pci device), using
+the raw address or id is sometimes problematic, for example:
+
+* when using HA, a different device with the same id or path may exist on the
+ target node, and if one is not careful when assigning such guests to HA
+ groups, the wrong device could be used, breaking configurations.
+
+* changing hardware can change ids and paths, so one would have to check all
+ assigned devices and see if the path or id is still correct.
+
+To handle this better, one can define cluster wide resource mappings, such that
+a resource has a cluster unique, user selected identifier which can correspond
+to different devices on different hosts. With this, HA won't start a guest with
+a wrong device, and hardware changes can be detected.
+
+Creating such a mapping can be done with the {pve} web GUI under `Datacenter`
+in the relevant tab in the `Resource Mappings` category, or on the cli with
+
+----
+# pvesh create /cluster/mapping/<type> <options>
+----
+
+[thumbnail="screenshot/gui-datacenter-mapping-pci-edit.png"]
+
+Where `<type>` is the hardware type (currently either `pci` or `usb`) and
+`<options>` are the device mappings and other configuration parameters.
+
+Note that the options must include a map property with all identifying
+properties of that hardware, so that it's possible to verify the hardware did
+not change and the correct device is passed through.
+
+For example to add a PCI device as `device1` with the path `0000:01:00.0` that
+has the device id `0001` and the vendor id `0002` on the node `node1`, and
+`0000:02:00.0` on `node2` you can add it with:
+
+----
+# pvesh create /cluster/mapping/pci --id device1 \
+ --map node=node1,path=0000:01:00.0,id=0002:0001 \
+ --map node=node2,path=0000:02:00.0,id=0002:0001
+----
+
+You must repeat the `map` parameter for each node where that device should have
+a mapping (note that you can currently only map one USB device per node per
+mapping).
+
+Using the GUI makes this much easier, as the correct properties are
+automatically picked up and sent to the API.
+
+[thumbnail="screenshot/gui-datacenter-mapping-usb-edit.png"]
+
+It's also possible for PCI devices to provide multiple devices per node with
+multiple map properties for the nodes. If such a device is assigned to a guest,
+the first free one will be used when the guest is started. The order of the
+paths given is also the order in which they are tried, so arbitrary allocation
+policies can be implemented.
+
+This is useful for devices with SR-IOV, since some times it is not important
+which exact virtual function is passed through.
+
+You can assign such a device to a guest either with the GUI or with
+
+----
+# qm set ID -hostpci0 <name>
+----
+
+for PCI devices, or
+
+----
+# qm set <vmid> -usb0 <name>
+----
+
+for USB devices.
+
+Where `<vmid>` is the guests id and `<name>` is the chosen name for the created
+mapping. All usual options for passing through the devices are allowed, such as
+`mdev`.
+
+To create mappings `Mapping.Modify` on `/mapping/<type>/<name>` is necessary
+(where `<type>` is the device type and `<name>` is the name of the mapping).
+
+To use these mappings, `Mapping.Use` on `/mapping/<type>/<name>` is necessary
+(in addition to the normal guest privileges to edit the configuration).
Managing Virtual Machines with `qm`
------------------------------------
-qm is the tool to manage Qemu/Kvm virtual machines on {pve}. You can
+qm is the tool to manage QEMU/KVM virtual machines on {pve}. You can
create and destroy virtual machines, and control execution
(start/stop/suspend/resume). Besides that, you can use qm to set
parameters in the associated config file. It is also possible to
Using an iso file uploaded on the 'local' storage, create a VM
with a 4 GB IDE disk on the 'local-lvm' storage
- qm create 300 -ide0 local-lvm:4 -net0 e1000 -cdrom local:iso/proxmox-mailgateway_2.1.iso
+----
+# qm create 300 -ide0 local-lvm:4 -net0 e1000 -cdrom local:iso/proxmox-mailgateway_2.1.iso
+----
Start the new VM
- qm start 300
+----
+# qm start 300
+----
Send a shutdown request, then wait until the VM is stopped.
- qm shutdown 300 && qm wait 300
+----
+# qm shutdown 300 && qm wait 300
+----
Same as above, but only wait for 40 seconds.
- qm shutdown 300 && qm wait 300 -timeout 40
+----
+# qm shutdown 300 && qm wait 300 -timeout 40
+----
+
+Destroying a VM always removes it from Access Control Lists and it always
+removes the firewall configuration of the VM. You have to activate
+'--purge', if you want to additionally remove the VM from replication jobs,
+backup jobs and HA resource configurations.
+
+----
+# qm destroy 300 --purge
+----
+
+Move a disk image to a different storage.
+
+----
+# qm move-disk 300 scsi0 other-storage
+----
+
+Reassign a disk image to a different VM. This will remove the disk `scsi1` from
+the source VM and attaches it as `scsi3` to the target VM. In the background
+the disk image is being renamed so that the name matches the new owner.
+
+----
+# qm move-disk 300 scsi1 --target-vmid 400 --target-disk scsi3
+----
[[qm_configuration]]
.Example VM Configuration
----
+boot: order=virtio0;net0
cores: 1
sockets: 1
memory: 512
name: webmail
ostype: l26
-bootdisk: virtio0
net0: e1000=EE:D2:28:5F:B6:3E,bridge=vmbr0
virtio0: local:vm-100-disk-1,size=32G
----
relationship between snapshots. `snaptime` is the snapshot creation
time stamp (Unix epoch).
+You can optionally save the memory of a running VM with the option `vmstate`.
+For details about how the target storage gets chosen for the VM state, see
+xref:qm_vmstatestorage[State storage selection] in the chapter
+xref:qm_hibernate[Hibernation].
[[qm_options]]
Options
Locks
-----
-Online migrations, snapshots and backups (`vzdump`) set a lock to
-prevent incompatible concurrent actions on the affected VMs. Sometimes
-you need to remove such a lock manually (e.g., after a power failure).
+Online migrations, snapshots and backups (`vzdump`) set a lock to prevent
+incompatible concurrent actions on the affected VMs. Sometimes you need to
+remove such a lock manually (for example after a power failure).
- qm unlock <vmid>
+----
+# qm unlock <vmid>
+----
CAUTION: Only do that if you are sure the action which set the lock is
no longer running.
+ifdef::wiki[]
+
+See Also
+~~~~~~~~
+
+* link:/wiki/Cloud-Init_Support[Cloud-Init Support]
+
+endif::wiki[]
+
ifdef::manvolnum[]
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