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1 | [[chapter_virtual_machines]] | |
2 | ifdef::manvolnum[] | |
3 | qm(1) | |
4 | ===== | |
5 | :pve-toplevel: | |
6 | ||
7 | NAME | |
8 | ---- | |
9 | ||
10 | qm - Qemu/KVM Virtual Machine Manager | |
11 | ||
12 | ||
13 | SYNOPSIS | |
14 | -------- | |
15 | ||
16 | include::qm.1-synopsis.adoc[] | |
17 | ||
18 | DESCRIPTION | |
19 | ----------- | |
20 | endif::manvolnum[] | |
21 | ifndef::manvolnum[] | |
22 | Qemu/KVM Virtual Machines | |
23 | ========================= | |
24 | :pve-toplevel: | |
25 | endif::manvolnum[] | |
26 | ||
27 | // deprecates | |
28 | // http://pve.proxmox.com/wiki/Container_and_Full_Virtualization | |
29 | // http://pve.proxmox.com/wiki/KVM | |
30 | // http://pve.proxmox.com/wiki/Qemu_Server | |
31 | ||
32 | Qemu (short form for Quick Emulator) is an open source hypervisor that emulates a | |
33 | physical computer. From the perspective of the host system where Qemu is | |
34 | running, Qemu is a user program which has access to a number of local resources | |
35 | like partitions, files, network cards which are then passed to an | |
36 | emulated computer which sees them as if they were real devices. | |
37 | ||
38 | A guest operating system running in the emulated computer accesses these | |
39 | devices, and runs as it were running on real hardware. For instance you can pass | |
40 | an iso image as a parameter to Qemu, and the OS running in the emulated computer | |
41 | will see a real CDROM inserted in a CD drive. | |
42 | ||
43 | Qemu can emulates a great variety of hardware from ARM to Sparc, but {pve} is | |
44 | only concerned with 32 and 64 bits PC clone emulation, since it represents the | |
45 | overwhelming majority of server hardware. The emulation of PC clones is also one | |
46 | of the fastest due to the availability of processor extensions which greatly | |
47 | speed up Qemu when the emulated architecture is the same as the host | |
48 | architecture. | |
49 | ||
50 | NOTE: You may sometimes encounter the term _KVM_ (Kernel-based Virtual Machine). | |
51 | It means that Qemu is running with the support of the virtualization processor | |
52 | extensions, via the Linux kvm module. In the context of {pve} _Qemu_ and | |
53 | _KVM_ can be use interchangeably as Qemu in {pve} will always try to load the kvm | |
54 | module. | |
55 | ||
56 | Qemu inside {pve} runs as a root process, since this is required to access block | |
57 | and PCI devices. | |
58 | ||
59 | ||
60 | Emulated devices and paravirtualized devices | |
61 | -------------------------------------------- | |
62 | ||
63 | The PC hardware emulated by Qemu includes a mainboard, network controllers, | |
64 | scsi, ide and sata controllers, serial ports (the complete list can be seen in | |
65 | the `kvm(1)` man page) all of them emulated in software. All these devices | |
66 | are the exact software equivalent of existing hardware devices, and if the OS | |
67 | running in the guest has the proper drivers it will use the devices as if it | |
68 | were running on real hardware. This allows Qemu to runs _unmodified_ operating | |
69 | systems. | |
70 | ||
71 | This however has a performance cost, as running in software what was meant to | |
72 | run in hardware involves a lot of extra work for the host CPU. To mitigate this, | |
73 | Qemu can present to the guest operating system _paravirtualized devices_, where | |
74 | the guest OS recognizes it is running inside Qemu and cooperates with the | |
75 | hypervisor. | |
76 | ||
77 | Qemu relies on the virtio virtualization standard, and is thus able to presente | |
78 | paravirtualized virtio devices, which includes a paravirtualized generic disk | |
79 | controller, a paravirtualized network card, a paravirtualized serial port, | |
80 | a paravirtualized SCSI controller, etc ... | |
81 | ||
82 | It is highly recommended to use the virtio devices whenever you can, as they | |
83 | provide a big performance improvement. Using the virtio generic disk controller | |
84 | versus an emulated IDE controller will double the sequential write throughput, | |
85 | as measured with `bonnie++(8)`. Using the virtio network interface can deliver | |
86 | up to three times the throughput of an emulated Intel E1000 network card, as | |
87 | measured with `iperf(1)`. footnote:[See this benchmark on the KVM wiki | |
88 | http://www.linux-kvm.org/page/Using_VirtIO_NIC] | |
89 | ||
90 | ||
91 | [[qm_virtual_machines_settings]] | |
92 | Virtual Machines Settings | |
93 | ------------------------- | |
94 | ||
95 | Generally speaking {pve} tries to choose sane defaults for virtual machines | |
96 | (VM). Make sure you understand the meaning of the settings you change, as it | |
97 | could incur a performance slowdown, or putting your data at risk. | |
98 | ||
99 | ||
100 | [[qm_general_settings]] | |
101 | General Settings | |
102 | ~~~~~~~~~~~~~~~~ | |
103 | ||
104 | [thumbnail="gui-create-vm-general.png"] | |
105 | ||
106 | General settings of a VM include | |
107 | ||
108 | * the *Node* : the physical server on which the VM will run | |
109 | * the *VM ID*: a unique number in this {pve} installation used to identify your VM | |
110 | * *Name*: a free form text string you can use to describe the VM | |
111 | * *Resource Pool*: a logical group of VMs | |
112 | ||
113 | ||
114 | [[qm_os_settings]] | |
115 | OS Settings | |
116 | ~~~~~~~~~~~ | |
117 | ||
118 | [thumbnail="gui-create-vm-os.png"] | |
119 | ||
120 | When creating a VM, setting the proper Operating System(OS) allows {pve} to | |
121 | optimize some low level parameters. For instance Windows OS expect the BIOS | |
122 | clock to use the local time, while Unix based OS expect the BIOS clock to have | |
123 | the UTC time. | |
124 | ||
125 | ||
126 | [[qm_hard_disk]] | |
127 | Hard Disk | |
128 | ~~~~~~~~~ | |
129 | ||
130 | Qemu can emulate a number of storage controllers: | |
131 | ||
132 | * the *IDE* controller, has a design which goes back to the 1984 PC/AT disk | |
133 | controller. Even if this controller has been superseded by more more designs, | |
134 | each and every OS you can think has support for it, making it a great choice | |
135 | if you want to run an OS released before 2003. You can connect up to 4 devices | |
136 | on this controller. | |
137 | ||
138 | * the *SATA* (Serial ATA) controller, dating from 2003, has a more modern | |
139 | design, allowing higher throughput and a greater number of devices to be | |
140 | connected. You can connect up to 6 devices on this controller. | |
141 | ||
142 | * the *SCSI* controller, designed in 1985, is commonly found on server grade | |
143 | hardware, and can connect up to 14 storage devices. {pve} emulates by default a | |
144 | LSI 53C895A controller. | |
145 | + | |
146 | A SCSI controller of type _VirtIO SCSI_ is the recommended setting if you aim for | |
147 | performance and is automatically selected for newly created Linux VMs since | |
148 | {pve} 4.3. Linux distributions have support for this controller since 2012, and | |
149 | FreeBSD since 2014. For Windows OSes, you need to provide an extra iso | |
150 | containing the drivers during the installation. | |
151 | // https://pve.proxmox.com/wiki/Paravirtualized_Block_Drivers_for_Windows#During_windows_installation. | |
152 | If you aim at maximum performance, you can select a SCSI controller of type | |
153 | _VirtIO SCSI single_ which will allow you to select the *IO Thread* option. | |
154 | When selecting _VirtIO SCSI single_ Qemu will create a new controller for | |
155 | each disk, instead of adding all disks to the same controller. | |
156 | ||
157 | * The *Virtio* controller, also called virtio-blk to distinguish from | |
158 | the VirtIO SCSI controller, is an older type of paravirtualized controller | |
159 | which has been superseded in features by the Virtio SCSI Controller. | |
160 | ||
161 | [thumbnail="gui-create-vm-hard-disk.png"] | |
162 | On each controller you attach a number of emulated hard disks, which are backed | |
163 | by a file or a block device residing in the configured storage. The choice of | |
164 | a storage type will determine the format of the hard disk image. Storages which | |
165 | present block devices (LVM, ZFS, Ceph) will require the *raw disk image format*, | |
166 | whereas files based storages (Ext4, NFS, GlusterFS) will let you to choose | |
167 | either the *raw disk image format* or the *QEMU image format*. | |
168 | ||
169 | * the *QEMU image format* is a copy on write format which allows snapshots, and | |
170 | thin provisioning of the disk image. | |
171 | * the *raw disk image* is a bit-to-bit image of a hard disk, similar to what | |
172 | you would get when executing the `dd` command on a block device in Linux. This | |
173 | format do not support thin provisioning or snapshotting by itself, requiring | |
174 | cooperation from the storage layer for these tasks. It is however 10% faster | |
175 | than the *QEMU image format*. footnote:[See this benchmark for details | |
176 | http://events.linuxfoundation.org/sites/events/files/slides/CloudOpen2013_Khoa_Huynh_v3.pdf] | |
177 | * the *VMware image format* only makes sense if you intend to import/export the | |
178 | disk image to other hypervisors. | |
179 | ||
180 | Setting the *Cache* mode of the hard drive will impact how the host system will | |
181 | notify the guest systems of block write completions. The *No cache* default | |
182 | means that the guest system will be notified that a write is complete when each | |
183 | block reaches the physical storage write queue, ignoring the host page cache. | |
184 | This provides a good balance between safety and speed. | |
185 | ||
186 | If you want the {pve} backup manager to skip a disk when doing a backup of a VM, | |
187 | you can set the *No backup* option on that disk. | |
188 | ||
189 | If you want the {pve} storage replication mechanism to skip a disk when starting | |
190 | a replication job, you can set the *Skip replication* option on that disk. | |
191 | As of {pve} 5.0, replication require the disk images to be on a storage of type | |
192 | `zfspool`, so adding a disk image to other storages when the VM has replication | |
193 | configured require to skip replication for this disk image. | |
194 | ||
195 | If your storage supports _thin provisioning_ (see the storage chapter in the | |
196 | {pve} guide), and your VM has a *SCSI* controller you can activate the *Discard* | |
197 | option on the hard disks connected to that controller. With *Discard* enabled, | |
198 | when the filesystem of a VM marks blocks as unused after removing files, the | |
199 | emulated SCSI controller will relay this information to the storage, which will | |
200 | then shrink the disk image accordingly. | |
201 | ||
202 | .IO Thread | |
203 | The option *IO Thread* can only be used when using a disk with the | |
204 | *VirtIO* controller, or with the *SCSI* controller, when the emulated controller | |
205 | type is *VirtIO SCSI single*. | |
206 | With this enabled, Qemu creates one I/O thread per storage controller, | |
207 | instead of a single thread for all I/O, so it increases performance when | |
208 | multiple disks are used and each disk has its own storage controller. | |
209 | Note that backups do not currently work with *IO Thread* enabled. | |
210 | ||
211 | ||
212 | [[qm_cpu]] | |
213 | CPU | |
214 | ~~~ | |
215 | ||
216 | [thumbnail="gui-create-vm-cpu.png"] | |
217 | ||
218 | A *CPU socket* is a physical slot on a PC motherboard where you can plug a CPU. | |
219 | This CPU can then contain one or many *cores*, which are independent | |
220 | processing units. Whether you have a single CPU socket with 4 cores, or two CPU | |
221 | sockets with two cores is mostly irrelevant from a performance point of view. | |
222 | However some software is licensed depending on the number of sockets you have in | |
223 | your machine, in that case it makes sense to set the number of of sockets to | |
224 | what the license allows you, and increase the number of cores. | |
225 | ||
226 | Increasing the number of virtual cpus (cores and sockets) will usually provide a | |
227 | performance improvement though that is heavily dependent on the use of the VM. | |
228 | Multithreaded applications will of course benefit from a large number of | |
229 | virtual cpus, as for each virtual cpu you add, Qemu will create a new thread of | |
230 | execution on the host system. If you're not sure about the workload of your VM, | |
231 | it is usually a safe bet to set the number of *Total cores* to 2. | |
232 | ||
233 | NOTE: It is perfectly safe to set the _overall_ number of total cores in all | |
234 | your VMs to be greater than the number of of cores you have on your server (ie. | |
235 | 4 VMs with each 4 Total cores running in a 8 core machine is OK) In that case | |
236 | the host system will balance the Qemu execution threads between your server | |
237 | cores just like if you were running a standard multithreaded application. | |
238 | However {pve} will prevent you to allocate on a _single_ machine more vcpus than | |
239 | physically available, as this will only bring the performance down due to the | |
240 | cost of context switches. | |
241 | ||
242 | Qemu can emulate a number different of *CPU types* from 486 to the latest Xeon | |
243 | processors. Each new processor generation adds new features, like hardware | |
244 | assisted 3d rendering, random number generation, memory protection, etc ... | |
245 | Usually you should select for your VM a processor type which closely matches the | |
246 | CPU of the host system, as it means that the host CPU features (also called _CPU | |
247 | flags_ ) will be available in your VMs. If you want an exact match, you can set | |
248 | the CPU type to *host* in which case the VM will have exactly the same CPU flags | |
249 | as your host system. | |
250 | ||
251 | This has a downside though. If you want to do a live migration of VMs between | |
252 | different hosts, your VM might end up on a new system with a different CPU type. | |
253 | If the CPU flags passed to the guest are missing, the qemu process will stop. To | |
254 | remedy this Qemu has also its own CPU type *kvm64*, that {pve} uses by defaults. | |
255 | kvm64 is a Pentium 4 look a like CPU type, which has a reduced CPU flags set, | |
256 | but is guaranteed to work everywhere. | |
257 | ||
258 | In short, if you care about live migration and moving VMs between nodes, leave | |
259 | the kvm64 default. If you don’t care about live migration, set the CPU type to | |
260 | host, as in theory this will give your guests maximum performance. | |
261 | ||
262 | You can also optionally emulate a *NUMA* architecture in your VMs. The basics of | |
263 | the NUMA architecture mean that instead of having a global memory pool available | |
264 | to all your cores, the memory is spread into local banks close to each socket. | |
265 | This can bring speed improvements as the memory bus is not a bottleneck | |
266 | anymore. If your system has a NUMA architecture footnote:[if the command | |
267 | `numactl --hardware | grep available` returns more than one node, then your host | |
268 | system has a NUMA architecture] we recommend to activate the option, as this | |
269 | will allow proper distribution of the VM resources on the host system. This | |
270 | option is also required in {pve} to allow hotplugging of cores and RAM to a VM. | |
271 | ||
272 | If the NUMA option is used, it is recommended to set the number of sockets to | |
273 | the number of sockets of the host system. | |
274 | ||
275 | ||
276 | [[qm_memory]] | |
277 | Memory | |
278 | ~~~~~~ | |
279 | ||
280 | For each VM you have the option to set a fixed size memory or asking | |
281 | {pve} to dynamically allocate memory based on the current RAM usage of the | |
282 | host. | |
283 | ||
284 | .Fixed Memory Allocation | |
285 | [thumbnail="gui-create-vm-memory-fixed.png"] | |
286 | ||
287 | When choosing a *fixed size memory* {pve} will simply allocate what you | |
288 | specify to your VM. | |
289 | ||
290 | Even when using a fixed memory size, the ballooning device gets added to the | |
291 | VM, because it delivers useful information such as how much memory the guest | |
292 | really uses. | |
293 | In general, you should leave *ballooning* enabled, but if you want to disable | |
294 | it (e.g. for debugging purposes), simply uncheck | |
295 | *Ballooning* or set | |
296 | ||
297 | balloon: 0 | |
298 | ||
299 | in the configuration. | |
300 | ||
301 | .Automatic Memory Allocation | |
302 | [thumbnail="gui-create-vm-memory-dynamic.png", float="left"] | |
303 | ||
304 | // see autoballoon() in pvestatd.pm | |
305 | When choosing to *automatically allocate memory*, {pve} will make sure that the | |
306 | minimum amount you specified is always available to the VM, and if RAM usage on | |
307 | the host is below 80%, will dynamically add memory to the guest up to the | |
308 | maximum memory specified. | |
309 | ||
310 | When the host is becoming short on RAM, the VM will then release some memory | |
311 | back to the host, swapping running processes if needed and starting the oom | |
312 | killer in last resort. The passing around of memory between host and guest is | |
313 | done via a special `balloon` kernel driver running inside the guest, which will | |
314 | grab or release memory pages from the host. | |
315 | footnote:[A good explanation of the inner workings of the balloon driver can be found here https://rwmj.wordpress.com/2010/07/17/virtio-balloon/] | |
316 | ||
317 | When multiple VMs use the autoallocate facility, it is possible to set a | |
318 | *Shares* coefficient which indicates the relative amount of the free host memory | |
319 | that each VM shoud take. Suppose for instance you have four VMs, three of them | |
320 | running a HTTP server and the last one is a database server. To cache more | |
321 | database blocks in the database server RAM, you would like to prioritize the | |
322 | database VM when spare RAM is available. For this you assign a Shares property | |
323 | of 3000 to the database VM, leaving the other VMs to the Shares default setting | |
324 | of 1000. The host server has 32GB of RAM, and is curring using 16GB, leaving 32 | |
325 | * 80/100 - 16 = 9GB RAM to be allocated to the VMs. The database VM will get 9 * | |
326 | 3000 / (3000 + 1000 + 1000 + 1000) = 4.5 GB extra RAM and each HTTP server will | |
327 | get 1/5 GB. | |
328 | ||
329 | All Linux distributions released after 2010 have the balloon kernel driver | |
330 | included. For Windows OSes, the balloon driver needs to be added manually and can | |
331 | incur a slowdown of the guest, so we don't recommend using it on critical | |
332 | systems. | |
333 | // see https://forum.proxmox.com/threads/solved-hyper-threading-vs-no-hyper-threading-fixed-vs-variable-memory.20265/ | |
334 | ||
335 | When allocating RAMs to your VMs, a good rule of thumb is always to leave 1GB | |
336 | of RAM available to the host. | |
337 | ||
338 | ||
339 | [[qm_network_device]] | |
340 | Network Device | |
341 | ~~~~~~~~~~~~~~ | |
342 | ||
343 | [thumbnail="gui-create-vm-network.png"] | |
344 | ||
345 | Each VM can have many _Network interface controllers_ (NIC), of four different | |
346 | types: | |
347 | ||
348 | * *Intel E1000* is the default, and emulates an Intel Gigabit network card. | |
349 | * the *VirtIO* paravirtualized NIC should be used if you aim for maximum | |
350 | performance. Like all VirtIO devices, the guest OS should have the proper driver | |
351 | installed. | |
352 | * the *Realtek 8139* emulates an older 100 MB/s network card, and should | |
353 | only be used when emulating older operating systems ( released before 2002 ) | |
354 | * the *vmxnet3* is another paravirtualized device, which should only be used | |
355 | when importing a VM from another hypervisor. | |
356 | ||
357 | {pve} will generate for each NIC a random *MAC address*, so that your VM is | |
358 | addressable on Ethernet networks. | |
359 | ||
360 | The NIC you added to the VM can follow one of two differents models: | |
361 | ||
362 | * in the default *Bridged mode* each virtual NIC is backed on the host by a | |
363 | _tap device_, ( a software loopback device simulating an Ethernet NIC ). This | |
364 | tap device is added to a bridge, by default vmbr0 in {pve}. In this mode, VMs | |
365 | have direct access to the Ethernet LAN on which the host is located. | |
366 | * in the alternative *NAT mode*, each virtual NIC will only communicate with | |
367 | the Qemu user networking stack, where a builting router and DHCP server can | |
368 | provide network access. This built-in DHCP will serve adresses in the private | |
369 | 10.0.2.0/24 range. The NAT mode is much slower than the bridged mode, and | |
370 | should only be used for testing. | |
371 | ||
372 | You can also skip adding a network device when creating a VM by selecting *No | |
373 | network device*. | |
374 | ||
375 | .Multiqueue | |
376 | If you are using the VirtIO driver, you can optionally activate the | |
377 | *Multiqueue* option. This option allows the guest OS to process networking | |
378 | packets using multiple virtual CPUs, providing an increase in the total number | |
379 | of packets transfered. | |
380 | ||
381 | //http://blog.vmsplice.net/2011/09/qemu-internals-vhost-architecture.html | |
382 | When using the VirtIO driver with {pve}, each NIC network queue is passed to the | |
383 | host kernel, where the queue will be processed by a kernel thread spawn by the | |
384 | vhost driver. With this option activated, it is possible to pass _multiple_ | |
385 | network queues to the host kernel for each NIC. | |
386 | ||
387 | //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 | |
388 | When using Multiqueue, it is recommended to set it to a value equal | |
389 | to the number of Total Cores of your guest. You also need to set in | |
390 | the VM the number of multi-purpose channels on each VirtIO NIC with the ethtool | |
391 | command: | |
392 | ||
393 | `ethtool -L eth0 combined X` | |
394 | ||
395 | where X is the number of the number of vcpus of the VM. | |
396 | ||
397 | You should note that setting the Multiqueue parameter to a value greater | |
398 | than one will increase the CPU load on the host and guest systems as the | |
399 | traffic increases. We recommend to set this option only when the VM has to | |
400 | process a great number of incoming connections, such as when the VM is running | |
401 | as a router, reverse proxy or a busy HTTP server doing long polling. | |
402 | ||
403 | ||
404 | [[qm_usb_passthrough]] | |
405 | USB Passthrough | |
406 | ~~~~~~~~~~~~~~~ | |
407 | ||
408 | There are two different types of USB passthrough devices: | |
409 | ||
410 | * Host USB passtrough | |
411 | * SPICE USB passthrough | |
412 | ||
413 | Host USB passthrough works by giving a VM a USB device of the host. | |
414 | This can either be done via the vendor- and product-id, or | |
415 | via the host bus and port. | |
416 | ||
417 | The vendor/product-id looks like this: *0123:abcd*, | |
418 | where *0123* is the id of the vendor, and *abcd* is the id | |
419 | of the product, meaning two pieces of the same usb device | |
420 | have the same id. | |
421 | ||
422 | The bus/port looks like this: *1-2.3.4*, where *1* is the bus | |
423 | and *2.3.4* is the port path. This represents the physical | |
424 | ports of your host (depending of the internal order of the | |
425 | usb controllers). | |
426 | ||
427 | If a device is present in a VM configuration when the VM starts up, | |
428 | but the device is not present in the host, the VM can boot without problems. | |
429 | As soon as the device/port ist available in the host, it gets passed through. | |
430 | ||
431 | WARNING: Using this kind of USB passthrough means that you cannot move | |
432 | a VM online to another host, since the hardware is only available | |
433 | on the host the VM is currently residing. | |
434 | ||
435 | The second type of passthrough is SPICE USB passthrough. This is useful | |
436 | if you use a SPICE client which supports it. If you add a SPICE USB port | |
437 | to your VM, you can passthrough a USB device from where your SPICE client is, | |
438 | directly to the VM (for example an input device or hardware dongle). | |
439 | ||
440 | ||
441 | [[qm_bios_and_uefi]] | |
442 | BIOS and UEFI | |
443 | ~~~~~~~~~~~~~ | |
444 | ||
445 | In order to properly emulate a computer, QEMU needs to use a firmware. | |
446 | By default QEMU uses *SeaBIOS* for this, which is an open-source, x86 BIOS | |
447 | implementation. SeaBIOS is a good choice for most standard setups. | |
448 | ||
449 | There are, however, some scenarios in which a BIOS is not a good firmware | |
450 | to boot from, e.g. if you want to do VGA passthrough. footnote:[Alex Williamson has a very good blog entry about this. | |
451 | http://vfio.blogspot.co.at/2014/08/primary-graphics-assignment-without-vga.html] | |
452 | In such cases, you should rather use *OVMF*, which is an open-source UEFI implemenation. footnote:[See the OVMF Project http://www.tianocore.org/ovmf/] | |
453 | ||
454 | If you want to use OVMF, there are several things to consider: | |
455 | ||
456 | In order to save things like the *boot order*, there needs to be an EFI Disk. | |
457 | This disk will be included in backups and snapshots, and there can only be one. | |
458 | ||
459 | You can create such a disk with the following command: | |
460 | ||
461 | qm set <vmid> -efidisk0 <storage>:1,format=<format> | |
462 | ||
463 | Where *<storage>* is the storage where you want to have the disk, and | |
464 | *<format>* is a format which the storage supports. Alternatively, you can | |
465 | create such a disk through the web interface with 'Add' -> 'EFI Disk' in the | |
466 | hardware section of a VM. | |
467 | ||
468 | When using OVMF with a virtual display (without VGA passthrough), | |
469 | you need to set the client resolution in the OVMF menu(which you can reach | |
470 | with a press of the ESC button during boot), or you have to choose | |
471 | SPICE as the display type. | |
472 | ||
473 | [[qm_startup_and_shutdown]] | |
474 | Automatic Start and Shutdown of Virtual Machines | |
475 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
476 | ||
477 | After creating your VMs, you probably want them to start automatically | |
478 | when the host system boots. For this you need to select the option 'Start at | |
479 | boot' from the 'Options' Tab of your VM in the web interface, or set it with | |
480 | the following command: | |
481 | ||
482 | qm set <vmid> -onboot 1 | |
483 | ||
484 | .Start and Shutdown Order | |
485 | ||
486 | [thumbnail="gui-qemu-edit-start-order.png"] | |
487 | ||
488 | In some case you want to be able to fine tune the boot order of your | |
489 | VMs, for instance if one of your VM is providing firewalling or DHCP | |
490 | to other guest systems. For this you can use the following | |
491 | parameters: | |
492 | ||
493 | * *Start/Shutdown order*: Defines the start order priority. E.g. set it to 1 if | |
494 | you want the VM to be the first to be started. (We use the reverse startup | |
495 | order for shutdown, so a machine with a start order of 1 would be the last to | |
496 | be shut down) | |
497 | * *Startup delay*: Defines the interval between this VM start and subsequent | |
498 | VMs starts . E.g. set it to 240 if you want to wait 240 seconds before starting | |
499 | other VMs. | |
500 | * *Shutdown timeout*: Defines the duration in seconds {pve} should wait | |
501 | for the VM to be offline after issuing a shutdown command. | |
502 | By default this value is set to 60, which means that {pve} will issue a | |
503 | shutdown request, wait 60s for the machine to be offline, and if after 60s | |
504 | the machine is still online will notify that the shutdown action failed. | |
505 | ||
506 | NOTE: VMs managed by the HA stack do not follow the 'start on boot' and | |
507 | 'boot order' options currently. Those VMs will be skipped by the startup and | |
508 | shutdown algorithm as the HA manager itself ensures that VMs get started and | |
509 | stopped. | |
510 | ||
511 | Please note that machines without a Start/Shutdown order parameter will always | |
512 | start after those where the parameter is set, and this parameter only | |
513 | makes sense between the machines running locally on a host, and not | |
514 | cluster-wide. | |
515 | ||
516 | ||
517 | [[qm_migration]] | |
518 | Migration | |
519 | --------- | |
520 | ||
521 | [thumbnail="gui-qemu-migrate.png"] | |
522 | ||
523 | If you have a cluster, you can migrate your VM to another host with | |
524 | ||
525 | qm migrate <vmid> <target> | |
526 | ||
527 | There are generally two mechanisms for this | |
528 | ||
529 | * Online Migration (aka Live Migration) | |
530 | * Offline Migration | |
531 | ||
532 | Online Migration | |
533 | ~~~~~~~~~~~~~~~~ | |
534 | ||
535 | When your VM is running and it has no local resources defined (such as disks | |
536 | on local storage, passed through devices, etc.) you can initiate a live | |
537 | migration with the -online flag. | |
538 | ||
539 | How it works | |
540 | ^^^^^^^^^^^^ | |
541 | ||
542 | This starts a Qemu Process on the target host with the 'incoming' flag, which | |
543 | means that the process starts and waits for the memory data and device states | |
544 | from the source Virtual Machine (since all other resources, e.g. disks, | |
545 | are shared, the memory content and device state are the only things left | |
546 | to transmit). | |
547 | ||
548 | Once this connection is established, the source begins to send the memory | |
549 | content asynchronously to the target. If the memory on the source changes, | |
550 | those sections are marked dirty and there will be another pass of sending data. | |
551 | This happens until the amount of data to send is so small that it can | |
552 | pause the VM on the source, send the remaining data to the target and start | |
553 | the VM on the target in under a second. | |
554 | ||
555 | Requirements | |
556 | ^^^^^^^^^^^^ | |
557 | ||
558 | For Live Migration to work, there are some things required: | |
559 | ||
560 | * The VM has no local resources (e.g. passed through devices, local disks, etc.) | |
561 | * The hosts are in the same {pve} cluster. | |
562 | * The hosts have a working (and reliable) network connection. | |
563 | * The target host must have the same or higher versions of the | |
564 | {pve} packages. (It *might* work the other way, but this is never guaranteed) | |
565 | ||
566 | Offline Migration | |
567 | ~~~~~~~~~~~~~~~~~ | |
568 | ||
569 | If you have local resources, you can still offline migrate your VMs, | |
570 | as long as all disk are on storages, which are defined on both hosts. | |
571 | Then the migration will copy the disk over the network to the target host. | |
572 | ||
573 | [[qm_copy_and_clone]] | |
574 | Copies and Clones | |
575 | ----------------- | |
576 | ||
577 | [thumbnail="gui-qemu-full-clone.png"] | |
578 | ||
579 | VM installation is usually done using an installation media (CD-ROM) | |
580 | from the operation system vendor. Depending on the OS, this can be a | |
581 | time consuming task one might want to avoid. | |
582 | ||
583 | An easy way to deploy many VMs of the same type is to copy an existing | |
584 | VM. We use the term 'clone' for such copies, and distinguish between | |
585 | 'linked' and 'full' clones. | |
586 | ||
587 | Full Clone:: | |
588 | ||
589 | The result of such copy is an independent VM. The | |
590 | new VM does not share any storage resources with the original. | |
591 | + | |
592 | ||
593 | It is possible to select a *Target Storage*, so one can use this to | |
594 | migrate a VM to a totally different storage. You can also change the | |
595 | disk image *Format* if the storage driver supports several formats. | |
596 | + | |
597 | ||
598 | NOTE: A full clone need to read and copy all VM image data. This is | |
599 | usually much slower than creating a linked clone. | |
600 | + | |
601 | ||
602 | Some storage types allows to copy a specific *Snapshot*, which | |
603 | defaults to the 'current' VM data. This also means that the final copy | |
604 | never includes any additional snapshots from the original VM. | |
605 | ||
606 | ||
607 | Linked Clone:: | |
608 | ||
609 | Modern storage drivers supports a way to generate fast linked | |
610 | clones. Such a clone is a writable copy whose initial contents are the | |
611 | same as the original data. Creating a linked clone is nearly | |
612 | instantaneous, and initially consumes no additional space. | |
613 | + | |
614 | ||
615 | They are called 'linked' because the new image still refers to the | |
616 | original. Unmodified data blocks are read from the original image, but | |
617 | modification are written (and afterwards read) from a new | |
618 | location. This technique is called 'Copy-on-write'. | |
619 | + | |
620 | ||
621 | This requires that the original volume is read-only. With {pve} one | |
622 | can convert any VM into a read-only <<qm_templates, Template>>). Such | |
623 | templates can later be used to create linked clones efficiently. | |
624 | + | |
625 | ||
626 | NOTE: You cannot delete the original template while linked clones | |
627 | exists. | |
628 | + | |
629 | ||
630 | It is not possible to change the *Target storage* for linked clones, | |
631 | because this is a storage internal feature. | |
632 | ||
633 | ||
634 | The *Target node* option allows you to create the new VM on a | |
635 | different node. The only restriction is that the VM is on shared | |
636 | storage, and that storage is also available on the target node. | |
637 | ||
638 | To avoid resource conflicts, all network interface MAC addresses gets | |
639 | randomized, and we generate a new 'UUID' for the VM BIOS (smbios1) | |
640 | setting. | |
641 | ||
642 | ||
643 | [[qm_templates]] | |
644 | Virtual Machine Templates | |
645 | ------------------------- | |
646 | ||
647 | One can convert a VM into a Template. Such templates are read-only, | |
648 | and you can use them to create linked clones. | |
649 | ||
650 | NOTE: It is not possible to start templates, because this would modify | |
651 | the disk images. If you want to change the template, create a linked | |
652 | clone and modify that. | |
653 | ||
654 | Importing Virtual Machines from foreign hypervisors | |
655 | --------------------------------------------------- | |
656 | ||
657 | A VM export from a foreign hypervisor takes usually the form of one or more disk | |
658 | images, with a configuration file describing the settings of the VM (RAM, | |
659 | number of cores). + | |
660 | The disk images can be in the vmdk format, if the disks come from | |
661 | VMware or VirtualBox, or qcow2 if the disks come from a KVM hypervisor. | |
662 | The most popular configuration format for VM exports is the OVF standard, but in | |
663 | practice interoperation is limited because many settings are not implemented in | |
664 | the standard itself, and hypervisors export the supplementary information | |
665 | in non-standard extensions. | |
666 | ||
667 | Besides the problem of format, importing disk images from other hypervisors | |
668 | may fail if the emulated hardware changes too much from one hypervisor to | |
669 | another. Windows VMs are particularly concerned by this, as the OS is very | |
670 | picky about any changes of hardware. This problem may be solved by | |
671 | installing the MergeIDE.zip utility available from the Internet before exporting | |
672 | and choosing a hard disk type of *IDE* before booting the imported Windows VM. | |
673 | ||
674 | Finally there is the question of paravirtualized drivers, which improve the | |
675 | speed of the emulated system and are specific to the hypervisor. | |
676 | GNU/Linux and other free Unix OSes have all the necessary drivers installed by | |
677 | default and you can switch to the paravirtualized drivers right after importing | |
678 | the VM. For Windows VMs, you need to install the Windows paravirtualized | |
679 | drivers by yourself. | |
680 | ||
681 | GNU/Linux and other free Unix can usually be imported without hassle. Note | |
682 | that we cannot guarantee a successful import/export of Windows WM in all | |
683 | cases due to the problems above. | |
684 | ||
685 | Step-by-step example of a Windows disk image import | |
686 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
687 | ||
688 | Microsoft provides | |
689 | https://developer.microsoft.com/en-us/microsoft-edge/tools/vms/[Virtual Machines exports] | |
690 | in different formats for browser testing. We are going to use one of these to | |
691 | demonstrate a VMDK import. | |
692 | ||
693 | Download the export zip | |
694 | ^^^^^^^^^^^^^^^^^^^^^^^ | |
695 | ||
696 | After getting informed about the user agreement, choose the _Microsoft Edge on | |
697 | Windows 10 Virtual Machine_ for the VMware platform, and download the zip. | |
698 | ||
699 | Extract the disk image from the zip | |
700 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
701 | ||
702 | Using the unzip utility or any archiver of your choice, unpack the zip, | |
703 | and copy via ssh/scp the vmdk file to your {pve} host. | |
704 | ||
705 | Create a new virtual machine and import the disk | |
706 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
707 | ||
708 | Create a virtual machine with 2 cores, 2GB RAM, and one NIC on the default | |
709 | +vmbr0+ bridge: | |
710 | ||
711 | qm create 999 -net0 e1000,bridge=vmbr0 -name Win10 -memory 2048 -bootdisk sata0 | |
712 | ||
713 | Import the disk image to the +local-lvm+ storage: | |
714 | ||
715 | qm importdisk 999 MSEdge "MSEdge - Win10_preview.vmdk" local-lvm | |
716 | ||
717 | The disk will be marked as *Unused* in the VM 999 configuration. | |
718 | After that you can go in the GUI, in the VM *Hardware*, *Edit* the unused disk | |
719 | and set the *Bus/Device* to *SATA/0*. | |
720 | The VM is ready to be started. | |
721 | ||
722 | ||
723 | Managing Virtual Machines with `qm` | |
724 | ------------------------------------ | |
725 | ||
726 | qm is the tool to manage Qemu/Kvm virtual machines on {pve}. You can | |
727 | create and destroy virtual machines, and control execution | |
728 | (start/stop/suspend/resume). Besides that, you can use qm to set | |
729 | parameters in the associated config file. It is also possible to | |
730 | create and delete virtual disks. | |
731 | ||
732 | CLI Usage Examples | |
733 | ~~~~~~~~~~~~~~~~~~ | |
734 | ||
735 | Using an iso file uploaded on the 'local' storage, create a VM | |
736 | with a 4 GB IDE disk on the 'local-lvm' storage | |
737 | ||
738 | qm create 300 -ide0 local-lvm:4 -net0 e1000 -cdrom local:iso/proxmox-mailgateway_2.1.iso | |
739 | ||
740 | Start the new VM | |
741 | ||
742 | qm start 300 | |
743 | ||
744 | Send a shutdown request, then wait until the VM is stopped. | |
745 | ||
746 | qm shutdown 300 && qm wait 300 | |
747 | ||
748 | Same as above, but only wait for 40 seconds. | |
749 | ||
750 | qm shutdown 300 && qm wait 300 -timeout 40 | |
751 | ||
752 | ||
753 | [[qm_configuration]] | |
754 | Configuration | |
755 | ------------- | |
756 | ||
757 | VM configuration files are stored inside the Proxmox cluster file | |
758 | system, and can be accessed at `/etc/pve/qemu-server/<VMID>.conf`. | |
759 | Like other files stored inside `/etc/pve/`, they get automatically | |
760 | replicated to all other cluster nodes. | |
761 | ||
762 | NOTE: VMIDs < 100 are reserved for internal purposes, and VMIDs need to be | |
763 | unique cluster wide. | |
764 | ||
765 | .Example VM Configuration | |
766 | ---- | |
767 | cores: 1 | |
768 | sockets: 1 | |
769 | memory: 512 | |
770 | name: webmail | |
771 | ostype: l26 | |
772 | bootdisk: virtio0 | |
773 | net0: e1000=EE:D2:28:5F:B6:3E,bridge=vmbr0 | |
774 | virtio0: local:vm-100-disk-1,size=32G | |
775 | ---- | |
776 | ||
777 | Those configuration files are simple text files, and you can edit them | |
778 | using a normal text editor (`vi`, `nano`, ...). This is sometimes | |
779 | useful to do small corrections, but keep in mind that you need to | |
780 | restart the VM to apply such changes. | |
781 | ||
782 | For that reason, it is usually better to use the `qm` command to | |
783 | generate and modify those files, or do the whole thing using the GUI. | |
784 | Our toolkit is smart enough to instantaneously apply most changes to | |
785 | running VM. This feature is called "hot plug", and there is no | |
786 | need to restart the VM in that case. | |
787 | ||
788 | ||
789 | File Format | |
790 | ~~~~~~~~~~~ | |
791 | ||
792 | VM configuration files use a simple colon separated key/value | |
793 | format. Each line has the following format: | |
794 | ||
795 | ----- | |
796 | # this is a comment | |
797 | OPTION: value | |
798 | ----- | |
799 | ||
800 | Blank lines in those files are ignored, and lines starting with a `#` | |
801 | character are treated as comments and are also ignored. | |
802 | ||
803 | ||
804 | [[qm_snapshots]] | |
805 | Snapshots | |
806 | ~~~~~~~~~ | |
807 | ||
808 | When you create a snapshot, `qm` stores the configuration at snapshot | |
809 | time into a separate snapshot section within the same configuration | |
810 | file. For example, after creating a snapshot called ``testsnapshot'', | |
811 | your configuration file will look like this: | |
812 | ||
813 | .VM configuration with snapshot | |
814 | ---- | |
815 | memory: 512 | |
816 | swap: 512 | |
817 | parent: testsnaphot | |
818 | ... | |
819 | ||
820 | [testsnaphot] | |
821 | memory: 512 | |
822 | swap: 512 | |
823 | snaptime: 1457170803 | |
824 | ... | |
825 | ---- | |
826 | ||
827 | There are a few snapshot related properties like `parent` and | |
828 | `snaptime`. The `parent` property is used to store the parent/child | |
829 | relationship between snapshots. `snaptime` is the snapshot creation | |
830 | time stamp (Unix epoch). | |
831 | ||
832 | ||
833 | [[qm_options]] | |
834 | Options | |
835 | ~~~~~~~ | |
836 | ||
837 | include::qm.conf.5-opts.adoc[] | |
838 | ||
839 | ||
840 | Locks | |
841 | ----- | |
842 | ||
843 | Online migrations, snapshots and backups (`vzdump`) set a lock to | |
844 | prevent incompatible concurrent actions on the affected VMs. Sometimes | |
845 | you need to remove such a lock manually (e.g., after a power failure). | |
846 | ||
847 | qm unlock <vmid> | |
848 | ||
849 | CAUTION: Only do that if you are sure the action which set the lock is | |
850 | no longer running. | |
851 | ||
852 | ||
853 | ifdef::manvolnum[] | |
854 | ||
855 | Files | |
856 | ------ | |
857 | ||
858 | `/etc/pve/qemu-server/<VMID>.conf`:: | |
859 | ||
860 | Configuration file for the VM '<VMID>'. | |
861 | ||
862 | ||
863 | include::pve-copyright.adoc[] | |
864 | endif::manvolnum[] |