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red811
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Full Name: Matt Spragg
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Hyper-V CSV HW VSS Issues - Failed Resources

Post by red811 » May 12, 2014 4:34 pm

Case REF: 00550469

We're currently using the following Components

Veeam B&R 7.0 Patch 3
Hyper-V 2012 R2 (all latest patches applied)
HP 3PAR 7400 Array
3PAR Hardware VSS Provider
Using Off-Host Backup Method

The Issue:
During backups we noticed that cluster resources were failing. The failed VMs were not necessarily the actual VMs being backed up at the time, but were instead always located on the CSV's that had hardware VSS snapshots created.

We tested using the diskshadow utility and experienced the same results with resources failing. Therefore, we took the issue up with HP/3PAR believing that their VSS provider was the cause.

However, after further testing it appeared that we were only using only the 3PAR VSS provider, using the following diskshadow command:

"set context persistent nowriters"

The "nowriters" option excluded the following additional writers:

Microsoft CSV Shadow Copy Helper Provider'

Microsoft CSV Shadow Copy Provider'

Including the writers (by removing the "nowriters" option) resolves the issue. As expected access to the CSV is briefly lost (paused) but resources do not fail. We also noticed that if application-aware image processing is enabled within the job it seems that the other providers are again included and the failures do not occur.

Summary:
Our requirement is to use crash-consistent backups for both windows and Linux VMs. It appears that when this method is used, Veeam is not including the other VSS writers required to maintain stability/availability of the CSV's during the snapshot creation.

Any ideas/suggestions would be very welcome!

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