virsh(1M) (man pages section 1M: System Administration Commands)

man pages section 1M: System Administration Commands

virsh(1M)

Name

virsh– management user interface for guest domains

Synopsis

virsh subcommand [arguments]

Description

The virsh command provides the main interface for command and control of both xVM and guest domains. Users should use virsh wherever possible, as it provides a generic and stable interface to controlling virtualized operating systems. Some xVM operations are not yet implemented by virsh. In those cases, the legacy utility xm(1M) can be used for detailed control.

virsh can be used to administer both transient and managed guests. A managed guest has a persistent configuration which is maintained across multiple invocations of the guest. The configuration of a transient guest is discarded when the guest shuts down.

With minor exceptions, the basic form of a virsh command is:

# virsh subcommand domain-id | name | uuid [options]

The components of a virsh command are described as follows:

subcommand: One of the subcommands described below.
domain-id | name | uuid: An identifier for a specific domain.
options: A subcommand-specific option.

Exceptions to command form described above occur when a subcommand acts on all domains, the entire machine, or directly on the Solaris xVM hypervisor.

Most virsh subcommands require root privileges or that you assume the Primary Administrator role.

Many virsh commands act asynchronously, so that the system prompt returns immediately while activity proceeds in the background. Many operations on domains, such as create and shutdown, can take considerable time (30 seconds or more) to reach completion. Use the list subcommand to determine whether such an operation is complete.

Subcommands

The virsh subcommands are categorized under the rubrics “generic”, “domain”, and “device” and are described in the following subsections of those names.

Generic Subcommands

capabilities

Display an XML document describing the capabilities of the hypervisor to which we are currently connected. This includes a section on the host capabilities in terms of CPU features, and a description for each kind of guest which can be virtualized. For a more complete description, see the page under libvirt.org entitled “XML Format”. The XML also shows the NUMA topology information, if available.

connect URI [--readonly]

Connect to the hypervisor. The URI parameter, if provided, specifies how to connect to the hypervisor. Without this parameter, the connection will be to the local hypervisor. The web page entitled “Connection URIs”, under libvirt.org, lists the possible values, but not all types are supported by all systems.

With the --readonly option, the connection is read-only.

help [subcommand]

With no argument, help displays a brief synopsis of all subcommands. With a specified subcommand, displays a brief description of that subcommand.

nodeinfo

Returns basic information about a node, such as the number and type of CPUs, and the size of physical memory.

quit

Quit this interactive terminal.

version

Display version information about this instance of virsh.

Domain Subcommands

The following subcommands manipulate domains directly. Most take a domain identifier as their first argument. In the following description, the notation domain can be either a symbolic domain name, a numeric domain id, or a UUID, any of which uniquely identify a domain.

console domain [--verbose]

Connect the virtual serial console for the guest. This subcommand takes the following option:

--verbose: Displays verbose connection and disconnection messages.

create file

Create (and start) a domain based on the parameters contained in the XML file file, where file is an absolute pathname. Such a file can be created using virsh dumpxml subcommand. Directly editing XML configuration is not recommended. Use this subcommand to create a transient guest. Use define (below) to create a managed guest.

define file [--relative-path path]

Define (but do not start) a domain from the specified XML file. If the disk paths in the XML file contain relative paths, the domain will be created with those paths relative to path, if provided.

destroy domain

Immediately terminate a domain. This is the equivalent of abruptly terminating power to a machine. In most cases, you should use the shutdown subcommand instead.

domid domain_name

Converts a domain name to a numeric domain ID.

dominfo domain

Returns basic information about a domain. In dominfo output, note that the OS Type field displays the type of virtualization--hvm for a Hardware-assisted Virtual Machine (HVM), linux for a paravirtualized domain--not the guest OS installed in a domain.

Note that, when the domain is running, dominfo displays dynamic data. Memory values include any hypervisor overhead.

domname domain_id

Converts a numeric domain id to a domain name.

domstate domain

Returns the state of a running domain. See the description of the list subcommand.

domuuid domain

Convert the specified domain name or ID to a domain UUID.

dump domain file

Dump the core of the domain specified by domain to the file specified by file for analysis.

dumpxml domain [--relative-path path]

Output the configuration of the given domain in XML format. Captured in a file, this data can be used as the argument to a subsequent create subcommand.

By default, all paths in the XML will be absolute. Adding the --relative-path option will make all disk paths relative to path.

edit

Starts the editor specified by the value of $EDITOR and, in this editor, opens the result of the command virsh dumpxml. The subcommand then redefines the domain with the edited XML. Editing XML is not recommended.

hostname

Returns the hostname of the control domain.

list [domain...]

Displays information about one or more domains. If no domains are specified, displays information about all defined domains. This subcommand takes the following options:

--active: Display only running domains.
--inactive: Display only non-running domains.
--all: Display both running and non-running domains.

By default, all domains are displayed.

An example of list output is as follows:

% virsh list
Id Name                 State

----------------------------------

0 Domain-0              running
2 fedora                paused
- solaris-hvm           shut off

Id is the numeric id for a domain; Name is the symbolic name. State is the run state and can be one of the following:

running: The domain is currently running on a CPU.
idle: The domain is not currently running on any CPU. This can be because the domain is waiting on I/O (a traditional wait state) or has gone to sleep because of inactivity.
paused: The domain has been paused, usually as a result of the administrator running virsh suspend. When in a paused state the domain still consumes allocated resources, such as memory, but is not eligible for scheduling by the xVM hypervisor.
in shutdown: The domain is in process of shutting down, but has not completely shutdown or crashed.
shut off: The domain is down.
crashed: The domain has crashed as a result of a sudden event. Normally, this state can occur only if the domain has been configured not to restart following a crash.

migrate --live | -–dryrun domain dest_uri [migrate_uri]

Migrate the domain to the host specified by dest_uri. The optional migrate_uri is a separate URI that specifies a transport method between the host and destination.

--live: Attempt a live migration.
-–dryrun: Use this option to test whether a domain can be migrated successfully to a remote host. This option works also on a non-running domain. Note that the checks are not necessarily complete: migration may still fail to work properly even if a dry-run migration passes.

reboot domain

Reboot a domain. The effect of this command is identical to the effect of running init 6. The command returns immediately, however, if successful, the entire reboot process might take a minute or more. There is no guarantee that the subcommand will succeed and it might take an unexpected length of time, depending on what services in the domain must be shutdown.

restore state-file

Restores a domain from a virsh save state file. See the description of the save subcommand.

resume domain

Moves a domain out of the paused state, making the domain eligible for scheduling by the underlying hypervisor.

save domain state-file

Saves a running domain to a file state-file, so that it can later be restored, using the restore subcommand. Once saved, the domain will no longer be running on the system, thus the memory allocated for the domain will be free for the use of other domains.

Note that network connections present before the save operation might be severed, as TCP timeouts might have expired.

schedinfo domain

Show or set the scheduling parameters for the specified domain name, ID or UUID. schedinfo works only on running domains. This subcommand takes the following options:

--weight number: weight for credit scheduler
--cap number: cap for credit scheduler
--set: Not implemented.

setmaxmem domain kilobytes

Change the maximum memory allocation limit in the specified guest domain. The kilobytes parameter is the maximum memory limit in kilobytes. If this subcommand is applied to a running domain, the specified value applies only after the domain has been rebooted.

setmem domain kilobytes

Change the current memory allocation in the specified guest domain. The kilobytes parameter is the number of kilobytes of memory. Note that only paravirtualized domains support changing this value by means of the balloon driver, and it cannot exceed the maximum memory limit for the domain . A Solaris paravirtualized domain can never exceed the memory value set at boot time.

setvcpus domain count

Change the number of virtual CPUs active in the specified guest domain. The count parameter is the number of virtual CPUs. Only paravirtualized domains can dynamically change this value, and only up to the value that was set at boot time. To change the number of CPUs in a way that persists, you must change the value when the domain is not running.

shutdown domain

Coordinates with the domain OS to perform graceful shutdown. The effect of this command is identical to the effect of running init 5. There is no guarantee that the subcommand will succeed and it might take an unexpected length of time, depending on what services in the domain must be shutdown.

start domain

Start a (previously defined) inactive domain.

suspend domain

Suspend a domain. When in this state, a domain still consumes allocated resources, such as memory, but is not eligible for scheduling by the xVM hypervisor.

ttyconsole

Return the pseudo-terminal used by the domain's serial console, if any.

undefine domain

Undefine the configuration for the inactive domain which is specified by either its domain name or UUID.

uri

Return the URI of the libvirt connection.

vcpuinfo domain

Return basic information about the domain virtual CPUs.

vcpupin domain vcpu cpulist

Pin domain VCPUs to the host physical CPUs. The domain parameter is the domain name, ID, or uuid. The vcpu parameter is the VCPU number. The cpulist parameter is a list of host CPU numbers, separated by commas.

This subcommand applies only to running domains.

vncdisplay domain

Output the IP address and port number for the VNC display.

Device Subcommands

The following subcommands manipulate devices associated with domains. In the following descriptions, domain can stand for either a symbolic domain name, a numeric domain id, or a UUID, any of which uniquely identify a domain.

attach-device domain file

Attach a device defined by the given XML file (file) to the specified domain.

attach-disk domain source target -–driver driver -–subdriver subdriver -–type type -–mode mode

Attach a new or existing disk device to the domain. A disk device can be a removable media device, such as a CD or DVD drive. source and target are paths for the files and devices. driver can be file, tap or phy, depending on the kind of access. type can indicate cdrom or floppy as an alternative to the default, disk. mode can specify either readonly or shareable.

Note that in a Solaris Hardware-assisted Virtual Machine (HVM) domU, you must run init(1M) in the domU to unlock a removable-media device (for example, a CD device) before running the attach-disk subcommand.

attach-interface domain type source -–target target -–mac mac -–script script -–capped-bandwidth bandwidth -–vlanid vid

Attach a new network interface to the domain. type must be bridge. source indicates the bridge interface. The -–target option is ignored. -–mac allows you to specify the MAC address of the network interface. -–script specifies a path to a script handling a bridge. A script value of vif-vnic (the default) will create a VNIC on top of the specified bridge NIC. A script value of vif-dedicated allows the guest to directly use the given NIC, which should not be configured in dom0.-–capped-bandwidth sets the bandwidth for this interface. Bandwidth should be specified as an integer with one of the scale suffixes (K, M, or G for Kbps, Mbps, or Gbps, respectively). Bandwidth will be rounded up to 1.2M, if the input number is smaller than that. -–vlanid sets the VLAN ID for this interface to vid.

detach-device domain file

Detach a device defined by the given XML file (file) from the specified domain. This subcommand takes the same type of XML descriptions as the subcommand attach-device.

detach-disk domain target

Detach a disk device from a domain. The target is the device as seen from the domain.

detach-interface domain type -–mac mac

Detach a network interface from a domain. type can be either network, to indicate a physical network device, or bridge, to indicate a bridge to a device. It is recommended you use the -–mac option to distinguish between the interfaces if more than one is present in the domain.

Examples

Example 1 Adding an ISO File to a Solaris Domain as a Virtual Disk

The following command adds an ISO file to a paravirtualized Solaris domain as a virtual disk /dev/dsk/c0t1d0.

# virsh attach-disk --type cdrom --driver file --mode readonly \
domu-220 /data.iso xvdb

Example 2 Migrating a Domain, Relying on `sshd` Configuration

To migrate a domain named domu to a machine named foo over ssh(1), first create the ssh connection:

# ssh -N -L 8003:localhost:8002 root@foo

...then run the virsh migrate command:

# virsh migrate --live domu xen:/// xenmigr://localhost:8003

This example assumes that TCP port forwarding is allowed by sshd_config(4). Note that this example does not require any modification of xend(1M) properties.

Example 3 Migrating a Domain, Relying on `xend` Configuration

The following virsh migrate command requires the proper setting of the xend xend-relocation-address and xend-relocation-hosts-allow properties, as described in the xend(1M) man page.

# virsh migrate --live domu xen:/// xenmigr://remotehost

Example 4 Changing a CD in a Solaris HVM Guest Domain

The following sequence of commands attaches a CD drive to a guest domain.

In the guest domain, eject the CD:

solaris-hvm# eject cdrom

Then, in the control domain, enter:

# virsh attach-disk solaris-hvm --type cdrom --driver file \
--mode readonly /isos/solaris.iso hdc

Finally, in the guest domain, load the CD:

solaris-hvm# rmformat

Example 5 Displaying `dominfo` Output

The following command displays information about domain 0.

# virsh dominfo Domain-0

Id:             0
Name:           Domain-0
UUID:           00000000-0000-0000-0000-000000000000
OS Type:        linux
State:          running
CPU(s):         4
CPU time:       14436.6s
Max memory:     no limit
Used memory:    3145728 kB

In the preceding output, note that the OS Type, linux, indicates a paravirtualized domain.

Example 6 Attaching an Interface

The following command attaches a new network interface to a guest domain, connected to the NIC e1000g0, with an auto-generated MAC address (that is, the --mac option is omitted).

# virsh attach-interface pv-domu bridge e1000g0

Example 7 Attaching a Disk

The following command attaches a disk generated by vdiskadm(1M) to a paravirtualized domain.

# virsh attach-disk domu-223 /disks/data.vdisk xvdb --driver \
tap --subdriver vdisk

Files

/usr/share/lib/xml/rng/libvirt: Relax-NG schemas for the XML formats used by libvirt and virsh.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWlibvirt
Interface Stability	Volatile

Authors

Andrew Puch, apuch at redhat dot com
Daniel Veillard, veillard at redhat dot com

The preceding authors credit the xm man page authored by:

Sean Dague, sean at dague dot net
Daniel Stekloff, dsteklof at us dot ibm dot com

Notes

Terminology differs between xm(1M) and virsh. In particular, the suspend and resume commands have different meanings.

virsh	xm
`suspend`	`pause`
`resume`	`unpause`
`save`	`suspend` (without output file argument)
`restore`	`resume` (without output file argument)

Terminology for the domain states differs between LDoms utilities, such as ldm, and virsh.

virsh	LDoms utility
`running`	`active`
`shut off`	`inactive`
`in shutdown`	`bound`

SunOS 5.11 Last Revised 11 Nov 2009