For the Xen server to function properly, the below daemons must be running on the VM server.
xend : This is the Xen server control daemon. This daemon must be running to start and manage the virtual machines. The administrative interface of xend is “xm”. The xend daemon can be customized using the configuration file /etc/xen/xend-config.sxp.
xendomains : This daemon helps on starting the guests automatically when the host server boots up. The Xen guest config file has to be placed in /etc/xen/auto/ for the xendomains to pickup and boot the guests when the server boots up.
libvirtd: This daemon allows the administrators to access the hypervisors and the virtual machines using management tools like “virsh” and “virt-install”.
Here are some more xm and virsh commands for creating, managing, and troubleshooting xen virtual machines.
List the guest domains: The command “xm list” displays the information of all running domains. The “–long” option displays full information on running guests.
In the output of “xm list”
- Name – represents the domU guest VM name
- ID -represents the domain ID
- Mem – represents the amount of memory allotted to the guest domain (in MB)
- VCPUs – represents the number of virtual CPUs assigned to a domain.
- State – represents the running state of the guest OS.
- r – running. The domain is currently running on a CPU.
- b – blocked. The domain is currently not running.
- p – paused. The domain is paused using “xm pause” command.
- c – crashed . The domain has crashed and terminated abruptly
- d – dying . The domain is the process of shutdown or crash.
- Time – represents the total runtime of the domain as accounted by the Xen server.
Starting a guest domain: The command “xm create” is used to startup a Xen guest. This command creates a guest based on the configuration file storage in /etc/xen.
If the Xen configuration file is not stored in /etc/xen, the file name with full path should be specified in “xm create” command.
Shutdown a guest: The command “xm shutdown” is used to shutdown an Xen guest gracefully.
[[email protected] ~]# xm shutdown guest06
Rebooting a guest: The command “xm reboot” is used to reboot a Xen domU guest.
Terminate a guest: The command “xm destroy” is used to immediately terminate an Xen domU guest virtual machine.
xm uptime – Displays uptime for a domain
xm top – Monitors a host and its domains in real time
xm list – Displays domain information
xm info – Displays host information
xm vcpu-list – Lists domain virtual processors
xm network-list – List virtual network interfaces for a domain.
virsh nodeinfo – Gives basic information about the node.
xm console – Attaches to a domain console
xm dump-core – Dumps core of a specific domain
xm dmesg – Reads and/or clears the xend daemon’s message buffer
xm log – Gives Xend log
virsh dominfo – Returns basic information about the domain
virsh dumpxml – Gives domain informations as an XML.
Xen Performance tuning
xm mem-max – Sets the maximum amount of memory for a domain
xm mem-set – Sets the current memory usage for a domain
xm vcpu-set – Sets the number of active processors for a domain
xm rename – Renames a domain
xm sysrq – Sends a system request to a domain
xm block-list – Lists virtual block devices for a domain