X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;ds=sidebyside;f=qm.adoc;h=b13f0f4ccb419222bb8dd3729e77801eb515a5a0;hb=52e23c357dcd2f8e632805867df6acd7e67e0d3b;hp=9ee4460e4ba00b788d99b3cc6f8fcc1f2e07f727;hpb=37422176c46632d2e3bb3df2b63da1b433da6bb4;p=pve-docs.git diff --git a/qm.adoc b/qm.adoc index 9ee4460..b13f0f4 100644 --- a/qm.adoc +++ b/qm.adoc @@ -150,6 +150,9 @@ one want's to pass through PCIe hardware. Hard Disk ~~~~~~~~~ +[[qm_hard_disk_bus]] +Bus/Controller +^^^^^^^^^^^^^^ Qemu can emulate a number of storage controllers: * the *IDE* controller, has a design which goes back to the 1984 PC/AT disk @@ -182,6 +185,10 @@ is an older type of paravirtualized controller. It has been superseded by the VirtIO SCSI Controller, in terms of features. [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 @@ -200,6 +207,9 @@ either the *raw disk image format* or the *QEMU image format*. * 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 @@ -215,6 +225,9 @@ As of {pve} 5.0, replication requires the disk images to be on a storage of type `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), you can activate the *Discard* option on a drive. With *Discard* set and a _TRIM_-enabled guest OS footnote:[TRIM, UNMAP, and discard @@ -232,14 +245,16 @@ 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. -.IO Thread + +[[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 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. +instead of a single thread for all I/O, so it can increase performance when +multiple isks are used and each disk has its own storage controller. [[qm_cpu]] @@ -268,8 +283,8 @@ 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. +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 @@ -507,7 +522,7 @@ host. .Fixed Memory Allocation [thumbnail="screenshot/gui-create-vm-memory.png"] -ghen setting memory and minimum memory to the same amount +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 @@ -856,6 +871,8 @@ 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 ^^^^^^^^^^^^^^^