View source for Qemu/KVM Virtual Machines

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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.
Qemu can emulates a great variety of hardware from ARM to Sparc, but Proxmox VE 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
architecture.
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 Proxmox VE Qemu and
KVM can be use interchangeably as Qemu in Proxmox VE will always try to load the kvm
module.
Qemu inside Proxmox VE 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 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
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
hypervisor.
Qemu relies on the virtio virtualization standard, and is thus able to presente
paravirtualized virtio devices, which includes a paravirtualized generic disk
controller, a paravirtualized network card, a paravirtualized serial port,
a paravirtualized SCSI controller, etc &#8230;
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). [See this benchmark on the KVM wiki
http://www.linux-kvm.org/page/Using_VirtIO_NIC]
Virtual Machines Settings
Generally speaking Proxmox VE tries to choose sane defaults for virtual machines
(VM). Make sure you understand the meaning of the settings you change, as it
could incur a performance slowdown, or putting your data at risk.
General Settings
General settings of a VM include
the Node : the physical server on which the VM will run
the VM ID: a unique number in this Proxmox VE installation used to identify your VM
Name: a free form text string you can use to describe the VM
Resource Pool: a logical group of VMs
OS Settings
When creating a VM, setting the proper Operating System(OS) allows Proxmox VE 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.
Hard Disk
Qemu can emulate a number of storage controllers:
the IDE controller, has a design which goes back to the 1984 PC/AT disk
controller. Even if this controller has been superseded by more more designs,
each and every OS you can think has support for it, making it a great choice
if you want to run an OS released before 2003. You can connect up to 4 devices
on this controller.
the SATA (Serial ATA) controller, dating from 2003, has a more modern
design, allowing higher throughput and a greater number of devices to be
connected. You can connect up to 6 devices on this controller.
the SCSI controller, designed in 1985, is commonly found on server grade
hardware, and can connect up to 14 storage devices. Proxmox VE emulates by default a
LSI 53C895A controller.
A SCSI controller of type Virtio is the recommended setting if you aim for
performance and is automatically selected for newly created Linux VMs since
Proxmox VE 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.
The Virtio controller, also called virtio-blk to distinguish from
the Virtio SCSI controller, is an older type of paravirtualized controller
which has been superseded in features by the Virtio SCSI Controller.
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
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
  thin provisioning of the disk image.
the raw disk image is a bit-to-bit image of a hard disk, similar to what
 you would get when executing the dd command on a block device in Linux. This
 format do not support thin provisioning or snapshotting by itself, requiring
 cooperation from the storage layer for these tasks. It is however 10% faster
  than the QEMU image format. [See this benchmark for details
 http://events.linuxfoundation.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.
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
block reaches the physical storage write queue, ignoring the host page cache.
This provides a good balance between safety and speed.
If you want the Proxmox VE backup manager to skip a disk when doing a backup of a VM,
you can set the No backup option on that disk.
If your storage supports thin provisioning (see the storage chapter in the
Proxmox VE 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 enabled when using a disk with the VirtIO controller,
or with the SCSI controller, when the emulated controller type is  VirtIO SCSI.
With this enabled, Qemu uses one thread per disk, instead of one thread for all,
so it should increase performance when using multiple disks.
Note that backups do not currently work with IO Thread enabled.
CPU
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
processing units. Whether you have a single CPU socket with 4 cores, or two CPU
sockets with two cores is mostly irrelevant from a performance point of view.
However some software is licensed depending on the number of sockets you have in
your machine, in that case it makes sense to set the number of of sockets to
what the license allows you, and increase the number of cores.
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
execution on the host system. If you&#8217;re not sure about the workload of your VM,
it is usually a safe bet to set the number of Total cores to 2.
It is perfectly safe to set the overall number of total cores in all
your VMs to be greater than the number of of cores you have on your server (ie.
4 VMs with each 4 Total cores running in a 8 core machine is OK) 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 Proxmox VE will prevent you to allocate on a single machine more vcpus than
physically available, as this will only bring the performance down due to the
cost of context switches.
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 &#8230;
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
the CPU type to host in which case the VM will have exactly the same CPU flags
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 Proxmox VE 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.
In short, if you care about live migration and moving VMs between nodes, leave
the kvm64 default. If you donât care about live migration, set the CPU type to
host, as in theory this will give your guests maximum performance.
You can also optionally emulate a NUMA architecture in your VMs. The basics of
the NUMA architecture mean that instead of having a global memory pool available
to all your cores, the memory is spread into local banks close to each socket.
This can bring speed improvements as the memory bus is not a bottleneck
anymore. If your system has a NUMA architecture [if the command
numactl --hardware | grep available returns more than one node, then your host
system has a NUMA architecture] we recommend to activate the option, as this
will allow proper distribution of the VM resources on the host system. This
option is also required in Proxmox VE to allow hotplugging of cores and RAM to 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.
Memory
For each VM you have the option to set a fixed size memory or asking
Proxmox VE to dynamically allocate memory based on the current RAM usage of the
host.
Fixed Memory Allocation
When choosing a fixed size memory Proxmox VE will simply allocate what you
specify to your VM.
Automatic Memory Allocation
When choosing to automatically allocate memory, Proxmox VE 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
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
grab or release memory pages from the host.
[A good explanation of the inner workings of the balloon driver can be found here https://rwmj.wordpress.com/2010/07/17/virtio-balloon/]
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 shoud 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
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 curring 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.
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
incur a slowdown of the guest, so we don&#8217;t recommend using it on critical
systems.
When allocating RAMs to your VMs, a good rule of thumb is always to leave 1GB
of RAM available to the host.
Network Device
Each VM can have many Network interface controllers (NIC), of four different
types:
Intel E1000 is the default, and emulates an Intel Gigabit network card.
the VirtIO paravirtualized NIC should be used if you aim for maximum
performance. Like all VirtIO devices, the guest OS should have the proper driver
installed.
the Realtek 8139 emulates an older 100 MB/s network card, and should
only be used when emulating older operating systems ( released before 2002 )
the vmxnet3 is another paravirtualized device, which should only be used
when importing a VM from another hypervisor.
Proxmox VE will generate for each NIC a random MAC address, so that your VM is
addressable on Ethernet networks.
The NIC you added to the VM can follow one of two differents models:
in the default Bridged mode each virtual NIC is backed on the host by a
tap device, ( a software loopback device simulating an Ethernet NIC ). This
tap device is added to a bridge, by default vmbr0 in Proxmox VE. 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 builting router and DHCP server can
provide network access. This built-in DHCP will serve adresses 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.
You can also skip adding a network device when creating a VM by selecting No
network device.
Multiqueue
If you are using the VirtIO driver, you can optionally activate the
Multiqueue option. This option allows the guest OS to process networking
packets using multiple virtual CPUs, providing an increase in the total number
of packets transfered.
When using the VirtIO driver with Proxmox VE, each NIC network queue is passed to the
host kernel, where the queue will be processed by a kernel thread spawn by the
vhost driver. With this option activated, it is possible to pass multiple
network queues to the host kernel for each NIC.
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:
ethtool -L eth0 combined X
where X is the number of the number of vcpus of the VM.
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
traffic increases. We recommend to set this option only when the VM has to
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.
USB Passthrough
There are two different types of USB passthrough devices:
Host USB passtrough
SPICE USB passthrough
Host USB passthrough works by giving a VM a USB device of the host.
This can either be done via the vendor- and product-id, or
via the host bus and port.
The vendor/product-id looks like this: 0123:abcd,
where 0123 is the id of the vendor, and abcd is the id
of the product, meaning two pieces of the same usb device
have the same id.
The bus/port looks like this: 1-2.3.4, where 1 is the bus
and 2.3.4 is the port path. This represents the physical
ports of your host (depending of the internal order of the
usb controllers).
If a device is present in a VM configuration when the VM starts up,
but the device is not present in the host, the VM can boot without problems.
As soon as the device/port ist available in the host, it gets passed through.
Using this kind of USB passthrough, means that you cannot move
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).
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. [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 implemenation. [See the OVMF Project http://www.tianocore.org/ovmf/]
If you want to use OVMF, there are several things to consider:
In order to save things like the boot order, there needs to be an EFI Disk.
This disk will be included in backups and snapshots, and there can only be one.
You can create such a disk with the following command:
qm set &lt;vmid&gt; -efidisk0 &lt;storage&gt;:1,format=&lt;format&gt;
Where &lt;storage&gt; is the storage where you want to have the disk, and
&lt;format&gt; is a format which the storage supports. Alternatively, you can
create such a disk through the web interface with Add &#8594; EFI Disk in the
hardware section of a VM.
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
with a press of the ESC button during boot), or you have to choose
SPICE as the display type.
Automatic Start and Shutdown of Virtual Machines
After creating your VMs, you probably want them to start automatically
when the host system boots. For this you need to select the option Start at
boot from the Options Tab of your VM in the web interface, or set it with
the following command:
qm set &lt;vmid&gt; -onboot 1
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)
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.
Shutdown timeout: Defines the duration in seconds Proxmox VE should wait
for the VM to be offline after issuing a shutdown command.
By default this value is set to 60, which means that Proxmox VE 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.
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
cluster-wide.
Managing Virtual Machines with qm
qm is the tool to manage Qemu/Kvm virtual machines on Proxmox VE. 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
create and delete virtual disks.
CLI Usage Examples
Create a new VM with 4 GB IDE disk.
qm create 300 -ide0 4 -net0 e1000 -cdrom proxmox-mailgateway_2.1.iso
Start the new VM
qm start 300
Send a shutdown request, then wait until the VM is stopped.
qm shutdown 300 &amp;&amp; qm wait 300
Same as above, but only wait for 40 seconds.
qm shutdown 300 &amp;&amp; qm wait 300 -timeout 40
Configuration
VM configuration files are stored inside the Proxmox cluster file
system, and can be accessed at /etc/pve/qemu-server/&lt;VMID&gt;.conf.
Like other files stored inside /etc/pve/, they get automatically
replicated to all other cluster nodes.
VMIDs &lt; 100 are reserved for internal purposes, and VMIDs need to be
unique cluster wide.
Example VM Configuration
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
Those configuration files are simple text files, and you can edit them
using a normal text editor (vi, nano, &#8230;). This is sometimes
useful to do small corrections, but keep in mind that you need to
restart the VM to apply such changes.
For that reason, it is usually better to use the qm command to
generate and modify those files, or do the whole thing using the GUI.
Our toolkit is smart enough to instantaneously apply most changes to
running VM. This feature is called "hot plug", and there is no
need to restart the VM in that case.
File Format
VM configuration files use a simple colon separated key/value
format. Each line has the following format:
# this is a comment
OPTION: value
Blank lines in those files are ignored, and lines starting with a #
character are treated as comments and are also ignored.
Snapshots
When you create a snapshot, qm stores the configuration at snapshot
time into a separate snapshot section within the same configuration
file. For example, after creating a snapshot called &#8220;testsnapshot&#8221;,
your configuration file will look like this:
VM configuration with snapshot
memory: 512
swap: 512
parent: testsnaphot
...
[testsnaphot]
memory: 512
swap: 512
snaptime: 1457170803
...
There are a few snapshot related properties like parent and
snaptime. The parent property is used to store the parent/child
relationship between snapshots. snaptime is the snapshot creation
time stamp (Unix epoch).
Options
acpi: &lt;boolean&gt; (default = 1)
Enable/disable ACPI.
agent: &lt;boolean&gt; (default = 0)
Enable/disable Qemu GuestAgent.
args: &lt;string&gt;
Arbitrary arguments passed to kvm, for example:
args: -no-reboot -no-hpet
this option is for experts only.
autostart: &lt;boolean&gt; (default = 0)
Automatic restart after crash (currently ignored).
balloon: &lt;integer&gt; (0 - N)
Amount of target RAM for the VM in MB. Using zero disables the ballon driver.
bios: &lt;ovmf | seabios&gt; (default = seabios)
Select BIOS implementation.
boot: [acdn]{1,4} (default = cdn)
Boot on floppy (a), hard disk (c), CD-ROM (d), or network (n).
bootdisk: (ide|sata|scsi|virtio)\d+
Enable booting from specified disk.
cdrom: &lt;volume&gt;
This is an alias for option -ide2
cores: &lt;integer&gt; (1 - N) (default = 1)
The number of cores per socket.
cpu: [cputype=]&lt;enum&gt; [,hidden=&lt;1|0&gt;]
Emulated CPU type.
cputype=&lt;486 | Broadwell | Broadwell-noTSX | Conroe | Haswell | Haswell-noTSX | IvyBridge | Nehalem | Opteron_G1 | Opteron_G2 | Opteron_G3 | Opteron_G4 | Opteron_G5 | Penryn | SandyBridge | Westmere | athlon | core2duo | coreduo | host | kvm32 | kvm64 | pentium | pentium2 | pentium3 | phenom | qemu32 | qemu64&gt; (default = kvm64)
Emulated CPU type.
hidden=&lt;boolean&gt; (default = 0)
Do not identify as a KVM virtual machine.
cpulimit: &lt;number&gt; (0 - 128) (default = 0)
Limit of CPU usage.
If the computer has 2 CPUs, it has total of 2 CPU time. Value 0 indicates no CPU limit.
cpuunits: &lt;integer&gt; (0 - 500000) (default = 1024)
CPU weight for a VM. Argument is used in the kernel fair scheduler. The larger the number is, the more CPU time this VM gets. Number is relative to weights of all the other running VMs.
You can disable fair-scheduler configuration by setting this to 0.
description: &lt;string&gt;
Description for the VM. Only used on the configuration web interface. This is saved as comment inside the configuration file.
efidisk0: [file=]&lt;volume&gt; [,format=&lt;enum&gt;] [,size=&lt;DiskSize&gt;]
Configure a Disk for storing EFI vars
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
freeze: &lt;boolean&gt;
Freeze CPU at startup (use c monitor command to start execution).
hostpci[n]: [host=]&lt;HOSTPCIID[;HOSTPCIID2...]&gt; [,pcie=&lt;1|0&gt;] [,rombar=&lt;1|0&gt;] [,x-vga=&lt;1|0&gt;]
Map host PCI devices into guest.
This option allows direct access to host hardware. So it is no longer
possible to migrate such machines - use with special care.
Experimental! User reported problems with this option.
host=&lt;HOSTPCIID[;HOSTPCIID2...]&gt;
Host PCI device pass through. The PCI ID of a host&#8217;s PCI device or a list
of PCI virtual functions of the host. HOSTPCIID syntax is:
bus:dev.func (hexadecimal numbers)
You can us the lspci command to list existing PCI devices.
pcie=&lt;boolean&gt; (default = 0)
Choose the PCI-express bus (needs the q35 machine model).
rombar=&lt;boolean&gt; (default = 1)
Specify whether or not the device&#8217;s ROM will be visible in the guest&#8217;s memory map.
x-vga=&lt;boolean&gt; (default = 0)
Enable vfio-vga device support.
hotplug: &lt;string&gt; (default = network,disk,usb)
Selectively enable hotplug features. This is a comma separated list of hotplug features: network, disk, cpu, memory and usb. Use 0 to disable hotplug completely. Value 1 is an alias for the default network,disk,usb.
hugepages: &lt;1024 | 2 | any&gt;
Enable/disable hugepages memory.
ide[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_length=&lt;seconds&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_length=&lt;seconds&gt;] [,iops_wr_max=&lt;iops&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,model=&lt;model&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;]
Use volume as IDE hard disk or CD-ROM (n is 0 to 3).
aio=&lt;native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
model=&lt;model&gt;
The drive&#8217;s reported model name, url-encoded, up to 40 bytes long.
rerror=&lt;ignore | report | stop&gt;
Read error action.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Whether the drive should be included when making snapshots.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
keyboard: &lt;da | de | de-ch | en-gb | en-us | es | fi | fr | fr-be | fr-ca | fr-ch | hu | is | it | ja | lt | mk | nl | no | pl | pt | pt-br | sl | sv | tr&gt; (default = en-us)
Keybord layout for vnc server. Default is read from the /etc/pve/datacenter.conf configuration file.
kvm: &lt;boolean&gt; (default = 1)
Enable/disable KVM hardware virtualization.
localtime: &lt;boolean&gt;
Set the real time clock to local time. This is enabled by default if ostype indicates a Microsoft OS.
lock: &lt;backup | migrate | rollback | snapshot&gt;
Lock/unlock the VM.
machine: (pc|pc(-i440fx)?-\d+\.\d+(\.pxe)?|q35|pc-q35-\d+\.\d+(\.pxe)?)
Specific the Qemu machine type.
memory: &lt;integer&gt; (16 - N) (default = 512)
Amount of RAM for the VM in MB. This is the maximum available memory when you use the balloon device.
migrate_downtime: &lt;number&gt; (0 - N) (default = 0.1)
Set maximum tolerated downtime (in seconds) for migrations.
migrate_speed: &lt;integer&gt; (0 - N) (default = 0)
Set maximum speed (in MB/s) for migrations. Value 0 is no limit.
name: &lt;string&gt;
Set a name for the VM. Only used on the configuration web interface.
net[n]: [model=]&lt;enum&gt; [,bridge=&lt;bridge&gt;] [,firewall=&lt;1|0&gt;] [,link_down=&lt;1|0&gt;] [,macaddr=&lt;XX:XX:XX:XX:XX:XX&gt;] [,queues=&lt;integer&gt;] [,rate=&lt;number&gt;] [,tag=&lt;integer&gt;] [,trunks=&lt;vlanid[;vlanid...]&gt;] [,&lt;model&gt;=&lt;macaddr&gt;]
Specify network devices.
bridge=&lt;bridge&gt;
Bridge to attach the network device to. The Proxmox VE standard bridge
is called vmbr0.
If you do not specify a bridge, we create a kvm user (NATed) network
device, which provides DHCP and DNS services. The following addresses
are used:
10.0.2.2   Gateway
10.0.2.3   DNS Server
10.0.2.4   SMB Server
The DHCP server assign addresses to the guest starting from 10.0.2.15.
firewall=&lt;boolean&gt;
Whether this interface should be protected by the firewall.
link_down=&lt;boolean&gt;
Whether this interface should be disconnected (like pulling the plug).
macaddr=&lt;XX:XX:XX:XX:XX:XX&gt;
MAC address. That address must be unique withing your network. This is automatically generated if not specified.
model=&lt;e1000 | e1000-82540em | e1000-82544gc | e1000-82545em | i82551 | i82557b | i82559er | ne2k_isa | ne2k_pci | pcnet | rtl8139 | virtio | vmxnet3&gt;
Network Card Model. The virtio model provides the best performance with very low CPU overhead. If your guest does not support this driver, it is usually best to use e1000.
queues=&lt;integer&gt; (0 - 16)
Number of packet queues to be used on the device.
rate=&lt;number&gt; (0 - N)
Rate limit in mbps (megabytes per second) as floating point number.
tag=&lt;integer&gt; (1 - 4094)
VLAN tag to apply to packets on this interface.
trunks=&lt;vlanid[;vlanid...]&gt;
VLAN trunks to pass through this interface.
numa: &lt;boolean&gt; (default = 0)
Enable/disable NUMA.
numa[n]: cpus=&lt;id[-id];...&gt; [,hostnodes=&lt;id[-id];...&gt;] [,memory=&lt;number&gt;] [,policy=&lt;preferred|bind|interleave&gt;]
NUMA topology.
cpus=&lt;id[-id];...&gt;
CPUs accessing this NUMA node.
hostnodes=&lt;id[-id];...&gt;
Host NUMA nodes to use.
memory=&lt;number&gt;
Amount of memory this NUMA node provides.
policy=&lt;bind | interleave | preferred&gt;
NUMA allocation policy.
onboot: &lt;boolean&gt; (default = 0)
Specifies whether a VM will be started during system bootup.
ostype: &lt;l24 | l26 | other | solaris | w2k | w2k3 | w2k8 | win7 | win8 | wvista | wxp&gt;
Specify guest operating system. This is used to enable special
optimization/features for specific operating systems:
other
unspecified OS
wxp
Microsoft Windows XP
w2k
Microsoft Windows 2000
w2k3
Microsoft Windows 2003
w2k8
Microsoft Windows 2008
wvista
Microsoft Windows Vista
win7
Microsoft Windows 7
win8
Microsoft Windows 8/2012
l24
Linux 2.4 Kernel
l26
Linux 2.6/3.X Kernel
solaris
Solaris/OpenSolaris/OpenIndiania kernel
parallel[n]: /dev/parport\d+|/dev/usb/lp\d+
Map host parallel devices (n is 0 to 2).
This option allows direct access to host hardware. So it is no longer possible to migrate such machines - use with special care.
Experimental! User reported problems with this option.
protection: &lt;boolean&gt; (default = 0)
Sets the protection flag of the VM. This will disable the remove VM and remove disk operations.
reboot: &lt;boolean&gt; (default = 1)
Allow reboot. If set to 0 the VM exit on reboot.
sata[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_length=&lt;seconds&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_length=&lt;seconds&gt;] [,iops_wr_max=&lt;iops&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;]
Use volume as SATA hard disk or CD-ROM (n is 0 to 5).
aio=&lt;native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
rerror=&lt;ignore | report | stop&gt;
Read error action.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Whether the drive should be included when making snapshots.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
scsi[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_length=&lt;seconds&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_length=&lt;seconds&gt;] [,iops_wr_max=&lt;iops&gt;] [,iothread=&lt;1|0&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,queues=&lt;integer&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;]
Use volume as SCSI hard disk or CD-ROM (n is 0 to 13).
aio=&lt;native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
iothread=&lt;boolean&gt;
Whether to use iothreads for this drive
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
queues=&lt;integer&gt; (2 - N)
Number of queues.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Whether the drive should be included when making snapshots.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
scsihw: &lt;lsi | lsi53c810 | megasas | pvscsi | virtio-scsi-pci | virtio-scsi-single&gt; (default = lsi)
SCSI controller model
serial[n]: (/dev/.+|socket)
Create a serial device inside the VM (n is 0 to 3), and pass through a
host serial device (i.e. /dev/ttyS0), or create a unix socket on the
host side (use qm terminal to open a terminal connection).
If you pass through a host serial device, it is no longer possible to migrate such machines - use with special care.
Experimental! User reported problems with this option.
shares: &lt;integer&gt; (0 - 50000) (default = 1000)
Amount of memory shares for auto-ballooning. The larger the number is, the more memory this VM gets. Number is relative to weights of all other running VMs. Using zero disables auto-ballooning
smbios1: [family=&lt;string&gt;] [,manufacturer=&lt;string&gt;] [,product=&lt;string&gt;] [,serial=&lt;string&gt;] [,sku=&lt;string&gt;] [,uuid=&lt;UUID&gt;] [,version=&lt;string&gt;]
Specify SMBIOS type 1 fields.
family=&lt;string&gt;
Set SMBIOS1 family string.
manufacturer=&lt;string&gt;
Set SMBIOS1 manufacturer.
product=&lt;string&gt;
Set SMBIOS1 product ID.
serial=&lt;string&gt;
Set SMBIOS1 serial number.
sku=&lt;string&gt;
Set SMBIOS1 SKU string.
uuid=&lt;UUID&gt;
Set SMBIOS1 UUID.
version=&lt;string&gt;
Set SMBIOS1 version.
smp: &lt;integer&gt; (1 - N) (default = 1)
The number of CPUs. Please use option -sockets instead.
sockets: &lt;integer&gt; (1 - N) (default = 1)
The number of CPU sockets.
startdate: (now | YYYY-MM-DD | YYYY-MM-DDTHH:MM:SS) (default = now)
Set the initial date of the real time clock. Valid format for date are: now or 2006-06-17T16:01:21 or 2006-06-17.
startup: `[[order=]\d+] [,up=\d+] [,down=\d+] `
Startup and shutdown behavior. Order is a non-negative number defining the general startup order. Shutdown in done with reverse ordering. Additionally you can set the up or down delay in seconds, which specifies a delay to wait before the next VM is started or stopped.
tablet: &lt;boolean&gt; (default = 1)
Enable/disable the USB tablet device. This device is usually needed to allow absolute mouse positioning with VNC. Else the mouse runs out of sync with normal VNC clients. If you&#8217;re running lots of console-only guests on one host, you may consider disabling this to save some context switches. This is turned off by default if you use spice (-vga=qxl).
tdf: &lt;boolean&gt; (default = 0)
Enable/disable time drift fix.
template: &lt;boolean&gt; (default = 0)
Enable/disable Template.
unused[n]: &lt;string&gt;
Reference to unused volumes. This is used internally, and should not be modified manually.
usb[n]: [host=]&lt;HOSTUSBDEVICE|spice&gt; [,usb3=&lt;1|0&gt;]
Configure an USB device (n is 0 to 4).
host=&lt;HOSTUSBDEVICE|spice&gt;
The Host USB device or port or the value spice. HOSTUSBDEVICE syntax is:
'bus-port(.port)*' (decimal numbers) or
'vendor_id:product_id' (hexadeciaml numbers) or
'spice'
You can use the lsusb -t command to list existing usb devices.
This option allows direct access to host hardware. So it is no longer possible to migrate such machines - use with special care.
The value spice can be used to add a usb redirection devices for spice.
usb3=&lt;boolean&gt; (default = 0)
Specifies whether if given host option is a USB3 device or port (this does currently not work reliably with spice redirection and is then ignored).
vcpus: &lt;integer&gt; (1 - N) (default = 0)
Number of hotplugged vcpus.
vga: &lt;cirrus | qxl | qxl2 | qxl3 | qxl4 | serial0 | serial1 | serial2 | serial3 | std | vmware&gt;
Select the VGA type. If you want to use high resolution modes (&gt;= 1280x1024x16) then you should use the options std or vmware. Default is std for win8/win7/w2k8, and cirrus for other OS types. The qxl option enables the SPICE display sever. For win* OS you can select how many independent displays you want, Linux guests can add displays them self. You can also run without any graphic card, using a serial device as terminal.
virtio[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_length=&lt;seconds&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_length=&lt;seconds&gt;] [,iops_wr_max=&lt;iops&gt;] [,iothread=&lt;1|0&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;]
Use volume as VIRTIO hard disk (n is 0 to 15).
aio=&lt;native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
iothread=&lt;boolean&gt;
Whether to use iothreads for this drive
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
rerror=&lt;ignore | report | stop&gt;
Read error action.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Whether the drive should be included when making snapshots.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
watchdog: [[model=]&lt;i6300esb|ib700&gt;] [,action=&lt;enum&gt;]
Create a virtual hardware watchdog device. Once enabled (by a guest action), the watchdog must be periodically polled by an agent inside the guest or else the watchdog will reset the guest (or execute the respective action specified)
action=&lt;debug | none | pause | poweroff | reset | shutdown&gt;
The action to perform if after activation the guest fails to poll the watchdog in time.
model=&lt;i6300esb | ib700&gt; (default = i6300esb)
Watchdog type to emulate.
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).
qm unlock &lt;vmid&gt;
Only do that if you are sure the action which set the lock is
no longer running.
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