Some users will use third party tool like netapp MBR alignment to align their VM vmdk to improve performance of the machine. After the vmdk alignment normal day to day operations work fine on the VM. However the backup of the VM fails.
Binary log message will report the failure as follow
Job Message 2012/03/12 11:20:34 3500 Data Plugin LDNNETVAULT1 Determining VM disk areas to backup
Information 2012/03/12 11:20:34 3500 Data Plugin LDNNETVAULT1 All sectors on disk '[ILIOStore] VDI-XP-ProdSupp/VDI-XP-ProdSupp-000011.vmdk' will be backed up
Error 2012/03/12 11:20:36 3500 Jobs LDNNETVAULT1 Job manager lost message channel unexpectedly
We have found that vmdk size as obtained from the snapshot is always zero after the alignement.
The VM has some snapshot prior to the alignment.
As per Vmware Support a VM must have all his snapshot removed before any alignment is done. Our test shows that if the VM had no snapshot prior to the alignment then the backup succeed. If a VM with existing snapshots is aligned its backup will fai.
If the VM is already aligned then the solution will be to revert the alignment , delete the snapshot(s), align the VM vmdk again and do the backup.
