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Hyper-V backups and white space

Created: 03 Jan 2013 • Updated: 22 Jul 2015 | 2 comments
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In Netbackup 7.5 is there an option to not backup the empty disk space when backing a Hyper-V VM? I know there is an option if you are backing up VMWare VMs but I can't see one for Hyper-V.



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RLeon's picture

The "Exclude deleted blocks" feature is only available for VMware.

I can only guess that there is some kind of technical limitation with VSS snapshots and fixed size vhd files sitting on top of NTFS in a Hyper-v host.

However, your problem can be solved with NetBackup deduplication (Nbu's own MSDP, or in general OST based dedup storage).
You will have to select "Enable file recovery from VM backup" in your Hyper-v policy for Nbu deduplication to really work well at the files as well as the "white space" inside vhd files.

Without Netbackup deduplication, to solve your problem the only option would be to use the traditional agent based backup method inside the guest OS.

Note that destination based 3rd party deduplication storage devices generally cannot deduplicate vhd files very well. Examples are VTLs or NAS storage devices with built-in deduplication capabilities.
Best to stick with Netbackup's own deduplication solutions.

Also, whether deduplication is used or not, vhd files in general do not compress well, even if alot of "white space" is present inside.

Mark_Solutions's picture

It is the vSphere API that gives the full capabilities for VMWare backups - unfortunately there is not that much integration at this time with Hyper-V (maybe reflected in the price difference between the two products?)

Authorised Symantec Consultant

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