Installation guide

Maintenance Procedures

vhd-update -f <filename> -j <filename>.journal

This will validate the specified journal file, then proceed to transform the bitmaps and rewrite

filename.

There is also a rollback operation

vhd-update -f <filename> -j <filename>.journal -r

which will write the bitmaps from filename.journal to filename without transforming them (this is

probably only useful for testing and debugging).

Note

• The vhd-update utility should not be used with live (i.e., plugged) VHDs.

• The vhd-update utility does not follow parent links; to update a chain of VHDs, each

file must be updated individually.

• While a VHD file is being updated, it will be marked as such so that the system will

not attempt to make use of it - this is to prevent it from being damaged. If you attempt

to use a VHD file that is in the process of being updated, or had an update operation

interrupted, it is normal for an error message to be displayed if you try to use it. If

the upgrade process is interrupted, please refer to the recovery instructions above for

information about how to restore the file back to its original state.

B.7. Backing up and restoring XenServer Hosts and VMs

We recommend that, whenever possible, you leave the installed state of XenServer Hosts unal-

tered. That is, do not install any additional packages or start additional services on XenServer

Hosts, and treat them as if they are appliances. The best way to restore, then, is to re-install

XenServer Host software from the installation media. If you have multiple XenServer Hosts, the

best approach is to configure a PXE boot server and appropriate answerfiles for this purpose

(see Appendix C, PXE installation of XenServer Host).

For VMs, the best approach is to install backup agents on them, just as if they were standard

physical servers. For Windows VMs, as of this release we have tested CA BrightStor ARCserve

Backup, and Symantec NetBackup and Backup Exec.

For more information about backup tools tested, best practices, and backups in general, see the

Citrix Knowledge Base.

B.7.1. Backing up Virtual Machine metadata

XenServer Hosts use a per-host database to store metadata about VMs and associated

resources such as storage and networking. When combined with storage repositories, this

database forms the complete view of all VMs available across the pool. Thus, it is important to

understand how to backup this database in order to recover from physical hardware failure and

other disaster scenarios.

This section first describes how to backup metadata for single-host installations, and then for

more complex pool setups.