This post is more than 5 years old
1 Rookie
•
51 Posts
0
148975
September 12th, 2014 00:00
2012 R2 Hyper-V and DPM not using SAN Snapshots anymore
Hi,
I installed a Hyper-V with DPM in April and made shure the DPM makes backups of the virtual machines by creating SAN snapshots through the VSS hardware provider.
Sometime in august it suddenly stopped using the VSS hardware provider.
I changed a lot since april, installed a Cluster, made the volumes as CSV, installed VMM. I did not find any error messages about the VSS provider. The dpmra logs finds the vss hardware provider. The backups are still working but only with software snapshots.
I can make VM snapshots of the affected VMs in ASM without issues. So the VSS hardware provider still works.
I did not changed the SAN firmware (7.0.5) or the HIT (4.7.0) since it worked.
I just opened a case with Microsoft, but if anyone have a clue what I could have changed or where I should look...
sbuerger
1 Rookie
•
51 Posts
1
September 15th, 2014 05:00
Microsoft just confirmed that this is a change in DPM 2012 R2 U3 when using Hyper-V on 2012 R2. They don't use the hw provider anymore. It is not documented in technet yet.
sbuerger
1 Rookie
•
51 Posts
0
September 15th, 2014 04:00
DPM 2012 R2 U3 and Windows Server 2012 R2 U1.
It's possible that I installed U3 after it was working. I'll check that.
Yes, DPM does not mount the snaps. The snaps are mounted on the hyper-v hosts.
As I understand, you will still gain some performance, because the virtual machine snaps could be merged after the volume snap is created. After the backup the volume snap would be deleted.
Without the hardware snap the virtual machine snaps have to be merged after the backup finishes, which could take some time and would make the merge slower.
sbuerger
1 Rookie
•
51 Posts
0
September 18th, 2014 07:00
The info I got:
DPM Backups today need Volume snapshot to get the stable copy of Application
• DPM now with Windows Server 2012 R2 can use VM snapshot to Backup instead of volume snapshot
• Volume Snapshot is avoided using Dummy VSS provider (DPM Null Provider)
• HyperV has made changes to give DPM and App consistent VM snapshot.
• Backups are done from Live Volume
• Hardware or software provider are not necessary anymore as DPM does not need volume snapshot.
Only Applicable to HyperV over Windows Server 2012 R2
• Prereq - support.microsoft.com/.../2919355
• Used only for CSV volume and Remote SMB. Not used for NTFS, REFS etc.
• Installed along with agent as separate service (VssNullProvider)
• Production Server Needs Reboot after patch installation before Null provider can work.
• “Vssadmin list providers” can be used to confirm the installation
VSS Provider priority in DPM
• Null Provider (default, can be disabled using Regkey)
• Software provider (if forced using Regkey)
• Default Provider (can be software or hardware)
To disable Null provider (on production server)
reg add "HKLM\Software\Microsoft\Microsoft Data Protection Manager\Agent" /v UseNullProvider /t REG_DWORD /d 0 /f