BE 2010 R2 - VMWare Agent - Full vs Inc strangeness

[Jeremy_Peake]

I am backing up a dozen VM machines using the vmware agent (vSphere 4.1) A couple machines are acting strange. Using a policy for full and inc vm backups On a couple machines, the vmdk file is 40GB, but the full backup jobs only report under 20GB as the backup size. However the inc backups report the full 40GB as the backup size. The backup rates are roughly the same, and the time is double for the incrementals.... This only seems to be the case on 2 of my virtual machines. I will be testing a restore to see what is actually getting backed up in the fulls. These are thick provisioned disks on a SAN. Has anyone seen this behaviour? Any insights?

[Jeremy_Peake]

ok, so i have noticed that the 2 Vm's that are acting this way are at VM hardware level 4, and all my other VM's are at 7. So maybe the lower level virtual hardware doesn't like incremental backups of vmdk's..... updating now, will report back here

[teiva-boy]

Level 7 is NEEDED to do incre/diff's with vStorage.  It's a requirement.

[Jim_S · Accepted solution]

Yep, definately need VMware Hardware Version 7 for any differnetial or incremental backups to work with any product.  Hardware Version 7 is what allows BackupExec 2010 to use vStorage APIs to enable Change Block Tracking on your VMs.  Once you update these to Hardware Version 7 you will need to perform a Full backup with your policy job prior to attempting another incremental.  If you browse the Datastore from vCenter client or CLI you should see XXXX_ctk.vmdk files cooresponding to each vmdk.

Also by default on a Full job BackupExec 2010R2 only backs up used space within your VMs, so if you have a 40GB VMDK, but only ~20GB is used space, you will see 20GB backed up.  Please make sure you're fully patched and on 2010R2 as there was a bug issue with this in earlier versions.

Another VMware thing that can toss a wrench in diff/incremental backup plans is the use of virtual-mode RDMs.  If there is a vRDM attached to a VM, BackupExec will ALWAYS perform a Full backup.

[Jeremy_Peake]

yep, hardware version 7 saves the day.  Awesome