Virtual Machine Backup

VMware suports hot backups and supports two technologies for backups

• Consolidated Backup
• Data Recovery Appliance

There are new features are

• The VMware Data Recovery appliance, a VM that faciliates backup and comes with the vSphere client plug-in
• Improvements in VMware Consolidated backup includes new support for thinly provisioned disks and IDE disks, improved support for busy SAN and iSCSI links, vApps and Windows Server 2008

It is possible to backup a running VM, this is achieved either by VMware or a 3rd party vendor leveraging VMware's snapshot feature. As discussed in my virtual machine section, when a snapshot is applied to a VM, the files that make up the VM becomes unlocked in the file system, when the files are unlocked it is possible to back them up. The only thing to worry about is the validation that the snapshots were successful prior to creating the backup and that they are deleted after the backup has finished or crashed, remember these snapshot files can grow to a very large size. VMware introduced a file system sync driver installed into the VM during the installation of VMware Tools. The job of this sync driver is to flush the file system cache, forcing a write-to-disk prior to the backup process, thus you b=get the most complete backup you can have with a live running VM. The newer version of the sync driver now has hooks into Microsoft's Volume Shadow Copy Service.

If you have a small environment or a laptop with VM running you could simply stop all the VM's and clone as templates in the compressed format to a different storage location. In a normal world you would backup the VM from the SAN itself, without the need for backup agents installed into the guest O/S, however many companies still install a backup agent (for example Netbackup) in the guest O/S.

VMware has developed it's own backup APIs which the conventional 3rd party vendors can hook into. The older VMware Data Recovery (VDR) appliance which is now deprecated, has been replaced with the newer VMware vSphere Data Protection (VDP)..