Posted by & filed under Xen.

Xen has states!

  • —r: the paravirtualised/hypervised “domain” is currently running some sort of process.
    A domain will not be in the running state (“r”) if it was just waiting for a packet to arrive or a mouse to be moved —
  • b: blocked, domain is waiting for something, usually an interrupt (for example, waiting for hard-disk data to be passed over to the domain). Also ,things like “sleep 5” in the shell would cause “blocked”, as the domain is waiting for a number of timer ticks (5 seconds worth of) to pass.
  • —p: paused – the domain has been paused with the command:xm pause (domain)
  • —c: crashed – when a paravirtualised domain (or an “enlightened” Windows install) crashes (kernel panic / BSOD etc) the hypervisor will detect this and put the machine into a crashed state.
  • d: dying – Something has told the domain to “kill itself” (such as “xm shutdown/destroy”, but it’s not yet disappeared. It’s probably there for the purpose of avoiding race-conditions where something is killing the domain, and something else is talking to it (for example disk accesses)

‘xm’

  • —The xm program is the main interface for managing Xen guest domains. The program can be used to create, pause, and shutdown domains. It can also be used to list current domains, enable or pin VCPUs, and attach or detach virtual block devices.
  • All xm operations rely upon the Xen control daemon, aka xend. For any xm commands to run xend must also be running. For this reason you should start xend as a service when your system first boots using xen.
  • —Most xm commands require root privileges to run due to the communications channels used to talk to the hypervisor. Running as non root will return an error.
  • Most xm commands act asynchronously, so just because the xm command returned, doesn’t mean the action is complete. This is important, as many operations on domains, like create and shutdown, can take considerable time (30 seconds or more) to bring the machine into a fully compliant state. If you want to know when one of these actions has finished you must poll through xm list periodically. —

xm create [-c] configfile [name=value]

  • The create sub command requires a config file and can optionally take a series of name value pairs that add to or override variables defined in the config file.
  • NOTE: Create will return as soon as the domain is started. This does not mean the guest OS in the domain has actually booted, or is available for input.
  • -c Attach console to the domain as soon as it has started. Useful for determining issues with crashing domains.

xm info

Print information about the Xen host in name : value format. When reporting a Xen bug, please provide this information as part of the bug report.

 host                   : tim-pxe-xc02
 release                : 2.6.32.3-timg
 version                : #1 Mon Jun 02 14:26:26 EST 2010
 machine                : x86_64
 nr_cpus                : 1
 nr_nodes               : 1
 sockets_per_node       : 1
 cores_per_socket       : 4
 threads_per_core       : 2
 cpu_mhz                : 3330
 hw_caps                : 0383fbff:00000000:00000000:00000040
 total_memory           : 16384
 free_memory            : 37
 xen_major              : 4
 xen_minor              : 0
 xen_extra              : -devel
 xen_caps               : xen-4.0.1-x86_64
 xen_pagesize           : 4096
 platform_params        : virt_start=0xfc000000
 xen_changeset          : Mon Nov 14 18:13:38 2010 +0100
                          21226:7dcfdd45bc9e
 cc_compiler            : gcc version 4.5.0
 cc_compile_by          : timg
 cc_compile_domain      : beast.timg.local
 cc_compile_date        : Mon May 21 12:16:48 EST 2010
 xend_config_format     : 2

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