22.1. virsh the command line interface tool for virtualization

22.1. `virsh` the command line interface tool for virtualization

The virsh command is an alternative command to manage a Red Hat Enterprise Linux 5 Xen environment using a Command Line Interface(CLI). The virsh command is provided as part of the libvirt API which provides a common API to applications requiring standardized access to interact with Xen using a stable interface. Besides providing virsh the libvirt API also provide a higher level language API for C, Python, and Perl (via the CPAN network) The virsh command is an interactive shell which can either be used in scripts or interactively. The following virsh commands assume you have already run virsh and are at a virsh# prompt.

Basic management options

The following are basic and commonly used virsh commands:

command	description
`help`	print help
`list`	list domains
`create`	create a domain from an XML file
`start`	start a previously created inactive domain
`destroy`	destroy a domain
`define`	define (but do not start) a domain from an XML file
`domid`	convert a domain name or UUID to domain id
`domuuid`	convert a domain name or id to domain UUID
`dominfo`	domain information
`domname`	convert a domain id or UUID to domain name
`domstate`	domain state
`quit`	quit this interactive terminal
`reboot`	reboot a domain
`restore`	restore a domain from a saved state in a file
`resume`	resume a domain
`save`	save a domain state to a file
`shutdown`	gracefully shutdown a domain
`suspend`	suspend a domain
`undefine`	undefine an inactive domain

Table 22.1. `virsh` commands

Resource management options

Use the following virsh commands to manage resources:

command	description
`setmem`	changes the allocated memory.
`setmaxmem`	changes maximum memory limit.
`setvcpus`	changes number of virtual CPUs.
`vcpuinfo`	domain vcpu information.
`vcpupin`	control the domain vcpu affinity.

Table 22.2. `virsh` resource management commands

Monitoring and troubleshooting options

Use the following virsh commands for monitoring and troubleshooting:

command	description
`version`	show version
`dumpxml`	domain information in XML
`nodeinfo`	node information

Table 22.3. `virsh` monitoring and troubleshooting commands

Presently unsupported options

The connect command that is used to connect or reconnect to a hypervisor.

`virsh` command output

The following are example outputs from common virsh commands:

the list command:

virsh # list
Id  Name                 State
----------------------------------
0   Domain-0             running
13  r5b2-mySQL01         blocked

the dominfo domain command:

virsh # dominfo r5b2-mySQL01
Id:             13
Name:           r5b2-mySQL01
UUID:           4a4c59a7-ee3f-c781-96e4-288f2862f011
OS Type:      	linux
State:          blocked
CPU(s):         1
CPU time:     	11.0s
Max memory:     512000 kB
Used memory:    512000 kB

the domstate domain command:
```
virsh # domstate r5b2-mySQL01
blocked
```

the domuuid domain command:

virsh # domuuid r5b2-mySQL01
4a4c59a7-ee3f-c781-96e4-288f2862f011

the vcpuinfo domain command:

virsh # vcpuinfo r5b2-mySQL01
VCPU:           0
CPU:            0
State:          blocked
CPU time:       0.0s
CPU Affinity:   yy

the dumpxm domain command:

virsh # dumpxml r5b2-mySQL01
<domain type='xen' id='13'>
	<name>r5b2-mySQL01</name>
	<uuid>4a4c59a7ee3fc78196e4288f2862f011</uuid>
	<bootloader>/usr/bin/pygrub</bootloader>
	<os>
		<type>linux</type>
		<kernel>/var/lib/xen/vmlinuz.2dgnU_</kernel>
		<initrd>/var/lib/xen/initrd.UQafMw</initrd>
		<cmdline>ro root=/dev/VolGroup00/LogVol00 rhgb quiet</cmdline>
	</os>
	<memory>512000</memory>
	<vcpu>1</vcpu>
	<on_poweroff>destroy</on_poweroff>
	<on_reboot>restart</on_reboot>
	<on_crash>restart</on_crash>
	<devices>
		<interface type='bridge'>
			<source bridge='xenbr0'/>
			<mac address='00:16:3e:49:1d:11'/>
			<script path='vif-bridge'/>
		</interface>
		<graphics type='vnc' port='5900'/>
		<console tty='/dev/pts/4'/>
  	</devices>

the version domain command:

virsh # version
Compiled against library: libvir 0.1.7
Using library: libvir 0.1.7
Using API: Xen 3.0.1
Running hypervisor: Xen 3.0.0