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