Chapter 28. The xm command quick reference

The xm command can manage the Xen hypervisor. Most operations can be performed with the libvirt tools, virt-manager application or the virsh command. The xm command does not have the error checking capacity of the libvirt tools and should not be used for tasks the libvirt tools support.
There are a few operations which currently can not be performed using virt-manager. Some options for other Xen implementations of the xm command do not work in Red Hat Enterprise Linux 5. The list below provides an overview of command options available and unavailable.

Warning

It is advised to use virsh or virt-manager instead of xm. The xm command does not handle error checking or configuration file errors very well and mistakes can lead to system instability or errors in virtual machines. Editing Xen configuration files manually is dangerous and should be avoided. Use this chapter at your own risk.
Basic management options

The following are basic and commonly used xm commands:

  • xm help [--long]: view available options and help text.
  • use the xm list command to list active domains: 
    $ xm list
Name                                ID  Mem(MiB)   VCPUs      State      Time(s)
Domain-0                            0     520       2         r-----     1275.5
r5b2-mySQL01                       13     500       1         -b----       16.1
  • xm create [-c] DomainName/ID: start a virtual machine. If the -c option is used, the start up process will attach to the guest's console.
  • xm console DomainName/ID: attach to a virtual machine's console.
  • xm destroy DomainName/ID: terminates a virtual machine , similar to a power off.
  • xm reboot DomainName/ID: reboot a virtual machine, runs through the normal system shut down and start up process.
  • xm shutdown DomainName/ID: shut down a virtual machine, runs a normal system shut down procedure.
  • xm pause
  • xm unpause
  • xm save
  • xm restore [-p] DomainName/ID: resume the state, and the execution of the domain. If the -p option is used, the domain will not be unpaused after restoring it.
  • xm migrate
Resource management options

Use the following xm commands to manage resources:

  • xm mem-set
  • use the xm vcpu-list to list virtualized CPU affinities: 
    $ xm vcpu-list
Name                          ID  VCPUs   CPU State  Time(s)  CPU Affinity
Domain-0                       0    0      0    r--   708.9    any cpu
Domain-0                       0    1      1   -b-    572.1    any cpu
r5b2-mySQL01                  13    0      1   -b-     16.1    any cpu
  • xm vcpu-pin
  • xm vcpu-set
  • use the xm sched-credit command to display scheduler parameters for a given domain: 
    $ xm sched-credit -d 0
{'cap': 0, 'weight': 256}
$ xm sched-credit -d 13
{'cap': 25, 'weight': 256}
Monitoring and troubleshooting options

Use the following xm commands for monitoring and troubleshooting:

  • xm top
  • xm dmesg
  • xm info
  • xm log
  • use the xm uptime to display the uptime of guests and hosts: 
    $ xm uptime
Name                       ID  Uptime
Domain-0                    0  3:42:18
r5b2-mySQL01               13  0:06:27
  • xm sysrq
  • xm dump-core
  • xm rename
  • xm domid
  • xm domname
Currently unsupported options

The xm vnet-list is currently unsupported.