KB2009120701: Citrix XenServer: how to access VServer images directly

In some situations it might be necessary to access the data or disk images of a Citrix XenServer VServer directly or to perform a manual file system check on a VServer partition. This document describes how to gain access via the xe tools supplied by Citrix:

An short overview of the xe commands and io layers and interfaces

xe pbd-|sr-|vdi-|vbd-|vm- (auto complete with TAB TAB) with
vm = virtual machine
vbd = virtual block device
vdi = virtual disk image
sr = storage repository
pbd = physical block device

After the object we specify the action as you can see in the following commands.

Step 1

Shut down the VM you want wo work on using XenCenter or xsconsole on the command line, otherwise the access will be not allowed.

Step 2

xe vm-list

Get the VM-UUID of the control domain labeled "Control domain on host: HOSTNAME".

Step 3

xe vbd-list vm-name-label=HOSTNAME

Get the VDI-UUID of the VDI on which you want to access directly. We recommend to assign names like HOSTNAME-system and HOSTNAME-backup to the VDIs in XenCenter. The devices you can see in the listing is the VDI name in the VM.

Step 4

xe vbd-create vm-uuid=VM-UUID vdi-uuid=VDI-UUID device=autodetect

This creates a VBD which allows the control domain to access the VDI of the VM. The command will return the VBD-UUID which we will need again.

Step 5

xe vbd-plug uuid=VBD-UUID

This command enables the VBD in the control domain. You should now see an additional disk and partitions in /proc/partitions, for example /dev/xvda1 and /dev/xvda2.

Step 6

That partitions can now
be accessed via mount or be checked via fsck the same way as regular partitions are.

Step 7

xe vbd-unplug uuid=VBD-UUID

If the partition is not mounted or accessed any more this command disables the VBD in the control domain again.

Step 8

xe vbd-destroy uuid=VBD-UUID

This command finally removes the temporary VBD created in the control domain to access the VDI of the VM.

Last change: 2009-12-10