I have a strange problem with IBM VSS-VDS hardware provider.
We have two sites with Veeam B&R 9.5 (running on physical servers). Each site have Hyper-V hosts in cluster (Windows 2012 R2 fail-over cluster) and Storwize v3700.
First site have FC switches and all servers are connected to V3700 via FC fabric. Second site do not have FC switches and all servers and Veeam are connected to V3700 directly.
Veeam is running backups in Off-Host proxy mode in each site. IBM VSS-VDS hardware provider is configured identically on both sites.
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C:\Program Files\IBM\Hardware Provider for VSS-VDS>ibmvcfg showcfg
username (cimom): superuser
Sometimes backup jobs on first site fails with "unknown status of async operation" error while Veeam is trying to create hardware VSS snapshot. Second site do not have such problems...
In Windows application event log on first site Hyper-V servers I can see VSS errors With ID 12298. There is one IBM KB article that describes it as "Microsoft VSS has a non configurable 10 second timeout to flush and hold VSS writers."
I have IBM VSS-VDS (V3700 hardware provider) log files from both sites, and from this log files I can see that there is a difference in actions what VSS-VDS performs during VSS snapshot creation:
1) On FIRST site VSS-VDS running on Hyper-V server creates FlashCopy snapshot, after that it mount this snapshot to HIMSELF, after that it unmounts snapshot from himself, and only later Veeam Off-Host proxy trying to mount snapshot. Sometimes Veeam fails.
(host6=VSS_FREE ; host7=VSS_RESERVED ; host4=Hyper-V ; host2=Veeam ; LUN1=CSV ; LUN2=VSS_snapshot)
2) On SECOND site VSS-VDS running on Hyper-V server creates FlashCopy snapshot and after that VSS-VDS running on Veeam Off-Host proxy successfully mounts it to himself. Everything is ok.
(host2=VSS_FREE ; host3=VSS_RESERVED ; host1=Veeam ; LUN1=CSV ; LUN2=VSS_snapshot)
So I guess that this extra (and useless) mount/unmount operations are the factor what slows down everything.
Is there any one who are using Veeam in Off-Host proxy mode with Storwize (or any other array) and with hardware VSS providers?
Do VSS provider in you environment performs mount/unmount to Hyper-V server before transfer VSS snapshot to Veeam Off-Host proxy?