topic Re: SnapManager for Hyper-V backup VM with pass-thru disk in Microsoft Virtualization Discussions

SnapManager for Hyper-V backup VM with pass-thru disk

wchong — Thu, 05 Jun 2025 07:09:39 GMT

Hi,

Would like to know anybody try to use SnapManager for Hyper-V to backup VM with pass-thru disk configured?

Because I configured one and it always failed. If the VM don't have any pass-thru disk configured, the backup will succeed.

Is the SnapManager for Hyper-V supported to backup VM with pass-thru disk?

Regards,

Wilson

Re: SnapManager for Hyper-V backup VM with pass-thru disk

amritad — Tue, 31 Aug 2010 03:58:46 GMT

SMHV can only backup VM data stored in VHDs that reside on NetApp storage. It doesn’t backup data on passthrough

or a direct attached iSCSI Disks. Also SMHV does not support MBR LUNs for VMs running on shared

volumes or CSVs.

Please take a look at TR 3805 that lists the best practices for SMHV.

Regards

Amrita

Re: SnapManager for Hyper-V backup VM with pass-thru disk

wchong — Tue, 31 Aug 2010 04:14:51 GMT

Hi Amrita,

Thanks for the info. I already read the TR-3805.

So now the confusion is if the VM's OS drive is a VHD and got the passthrough disk configured for application data, can we still use SMHV to backup it?

From my understand, SMHV should be able to continue to backup the VM for the OS and skip the passthrough disk, am i right?

But now the actual fact is the whole backup set will failed and nothing is being backup.

Regards,

Wilson

Re: SnapManager for Hyper-V backup VM with pass-thru disk

barve — Tue, 31 Aug 2010 05:38:17 GMT

Yes, SMHV should be able to backup the VM with pass through disks attached to it. Pass through disks will be skipped from backup, so the data on pass through disks won’t get backed up. However, VM backup should succeed.

Please open a case with support if the backup is failing.

Thanks,

Anagha

Re: SnapManager for Hyper-V backup VM with pass-thru disk

wchong — Tue, 31 Aug 2010 06:00:32 GMT

Hi Anagha,

We already open a case with support. But after analysis, the log just mentioned the VSS backup is failed, so cause the whole backup is failed.

Not sure is there any special configuration or hotfix need to be install for the config to work.

Regards,

Wilson

Re: SnapManager for Hyper-V backup VM with pass-thru disk

barve — Tue, 31 Aug 2010 06:39:47 GMT

We need to first see why the VSS backup failed. There could be various reasons for VSS backup failure, so once we determine the exact cause, we can see how to resolve the issue.

Thanks,

Anagha

Re: SnapManager for Hyper-V backup VM with pass-thru disk

vkarinta — Tue, 31 Aug 2010 07:25:13 GMT

VSS backup can fail because of nuemerous reasons, As a quick check can you please verify whether you have the following hotfix installed on your Hyper-V parent?

http://support.microsoft.com/kb/975354

If you dont have this hot fix Please download and install this hotfix on the parent Hyper-V host and then update the integration services in the VM 
using following menu item 
Action -> "Insert Integration Services Setup Disk". Retry the backup after the integration service is updated for the VM.

If the problem still exists, please upload the ontapwindc from the Hyper-V parent to NGS.

I would also like to know whether you have SnapDrive for Windows installed on the guest VM?

Thanks,
Vineeth

Re: SnapManager for Hyper-V backup VM with pass-thru disk

wchong — Tue, 31 Aug 2010 16:19:06 GMT

Thanks for the info. This implementation is done by partner and after verified, I also found out the hotfilx is not installed in the parent host, so i already asked them to install it and try again.

The SnapDrive is installed in the guest VM, because it run Exchange, and using SME for backup.

Regards,

Wilson

Re: SnapManager for Hyper-V backup VM with pass-thru disk

vkarinta — Tue, 31 Aug 2010 16:30:20 GMT

Thanks for the information. There was a known backup performance issue(or some times even the backup fails)

when using the pas-through disk/iscsi LUNs in the VM with the SnapDrive installed.

Following is the SMHV 1.0 Release note entry describing this issue.

----------------------------------------------------------------------------------------------------

If a virtual machine contains several direct-attached iSCSI LUNs or pass-through LUNs, and SnapDrive
for Windows is installed on the virtual machine, the virtual machine backup can take a long time.

The Hyper-V writer takes a hardware snapshot of all the LUNs in the virtual machine using the SnapDrive

for Windows VSS hardware provider. MS hotfix 975354 will use the default software provider
in the virtual machine to take the snapshot. SnapManager for Hyper-V does not use the SnapDrive for
Windows VSS hardware provider for snapshot creation inside the child OS and the backup speed increases.

Thanks,

Vineeth