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→Performing the Migration
After a short period of time the guest domain will no longer appear on the list of guests on the source host and will now be running on the target host.
== Checking the Xen Log ==
The migration from a user's perspective is a silent process. This can make tracking down problems since a failed migration will not report anything on the command-line. If problems are encountered during the migration the first place to look for information is the Xen log file which can be viewed by running the ''xm log'' command. The following shows partial output from a successful live migration:
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[2008-06-11 15:46:02 xend 2404] DEBUG (balloon:127) Balloon: 132008 KiB free; need 131072; done.
[2008-06-11 15:46:02 xend 2404] DEBUG (XendCheckpoint:215) [xc_restore]: /usr/lib/xen/bin/xc_restore 16 1 1 2 0 0 0
[2008-06-11 15:46:04 xend 2404] INFO (XendCheckpoint:351) xc_domain_restore start: p2m_size = 8800
[2008-06-11 15:46:04 xend 2404] INFO (XendCheckpoint:351) Reloading memory pages: 0%
[2008-06-11 15:46:47 xend 2404] INFO (XendCheckpoint:351) Received all pages (0 races)
[2008-06-11 15:46:47 xend 2404] INFO (XendCheckpoint:3100%
[2008-06-11 15:46:47 xend 2404] INFO (XendCheckpoint:351) Memory reloaded (4440 pages)
[2008-06-11 15:46:47 xend 2404] INFO (XendCheckpoint:351) Domain ready to be built.
[2008-06-11 15:46:47 xend 2404] INFO (XendCheckpoint:351) Restore exit with rc=0
[2008-06-11 15:46:47 xend 2404] DEBUG (XendCheckpoint:322) store-mfn 5108
[2008-06-11 15:46:47 xend 2404] DEBUG (XendCheckpoint:322) console-mfn 128698
[2008-06-11 15:46:48 xend.XendDomainInfo 2404] DEBUG (XendDomainInfo:691) XendDomainInfo.completeRestore
[2008-06-11 15:46:49 xend.XendDomainInfo 2404] DEBUG (XendDomainInfo:791) Storing domain details: {\047console/ring-ref\047: \047128698\047, \047console/port\047: \0472\047, \047name\047: \047centos.5-1\047, \047console/limit\047: \0471048576\047, \047vm\047: \047/vm/bd0c2520-1094-0b71-a3ed-c6a5f917f235\047, \047domid\047: \0471\047, \047cpu/0/availability\047: \047online\047, \047memory/target\047: \047131072\047, \047store/ring-ref\047: \0475108\047, \047store/port\047: \0471\047}
[2008-06-11 15:46:49 xend.XendDomainInfo 2404] DEBUG (XendDomainInfo:707) XendDomainInfo.completeRestore done
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices vif.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:149) Waiting for 0.
[2008-06-11 15:46:49 xend.XendDomainInfo 2404] DEBUG (XendDomainInfo:988) XendDomainInfo.handleShutdownWatch
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:476) hotplugStatusCallback /local/domain/0/backend/vif/1/0/hotplug-status.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:490) hotplugStatusCallback 1.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices usb.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices vbd.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices irq.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices vkbd.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices vfb.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices pci.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices ioports.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices tap.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:149) Waiting for 51713.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:476) hotplugStatusCallback /local/domain/0/backend/tap/1/51713/hotplug-status.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:490) hotplugStatusCallback 1.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:149) Waiting for 51714.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:476) hotplugStatusCallback /local/domain/0/backend/tap/1/51714/hotplug-status.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:490) hotplugStatusCallback 1.
[2008-06-11 15:46:49 xend 2404] DEBUG (DevController:143) Waiting for devices vtpm.
</pre>
If the migration fails the log output will likely differ in some signicant way from the above example. A common cause for the migration failing is the result of there being insufficient memory on the target system to accommodate the guest domain.
