Why DPM can only take offline backup for some VMs under Hyper-V 2012R2 Host ? Need SCSI !!

Posted by Ahmed Nabil In , | 9 comments»
I published a recent article on migrating/moving VMs from 2008R2 to 2012R2 Hyper-V host (you can check it at http://itcalls.blogspot.com/2013/11/how-to-migratemove-virtual-machines.html ), after successfully moving these VMs we faced another problem trying to backup them. We were using the latest DPM 2012R2 and we noticed that it added these VMs as offline only and for some reason it can't take online backup of them.

After some investigation we noticed an error on the hyper-v host with Event ID 10103 (check below image) which clearly mention that backup will fail because this VM doesn't have a SCSI controller.


So the solution was just to add a SCSI controller even if its connected to nothing, after that online/hot backup was taken smoothly without any problem.

So what was the problem ?

I discussed this issue with several Microsoft support personnel and It turned out that online or hot backup for a VM in 2012R2 Hyper-V host requires mounting a new VHD in the VM and then dismounting it later. Since only the SCSI controller can mount/support hot plugging of virtual disks, it became clear why we need this SCSI controller.

Old version of Hyper-V didn't work this way,  it required that the Hyper-V host mount the guest VHD as part of the backup process which is something Microsoft didn't like as it increase the surface of attack on this host.


9 Comments
Comments

9 comments:

R.K L Says:

thanks for the information. this is happening to me..

Anonymous Says:

Thank you Ahmed for sharing with us! Really helpful.

theruck242 Says:

you are unfrotunatelly wrong

By default, DPM backs up virtual machines in an online state. However, if any of the following conditions are true that are set by the Hyper-V writer, DPM performs backups in an offline state:

The Backup (Volume Snapshot) Integration Service is disabled or not installed.

A virtual machine has one or more dynamic disks.

A virtual machine has one or more volumes that are based on non-NTFS file systems.

In a cluster configuration, the virtual machine Cluster Resource Group is offline.

A virtual machine is not in a running state.

A Shadow Storage assignment of a volume inside the virtual machine is explicitly set to a different volume other than itself.

Ahmed Nabil Says:

You need to have SCSI controller, the error is clear in the logs as per attached. You can still have the IDE.

Nicolas Desgroseilliers Says:

Hi! I Have a problem that is slightly different... I do not have any errors, but DPM only gives me the option to have offline backup of my VM.

I also noticed that the VM created with SCVMM 2012 R2 were available online in DPM. But not the "old" ones (2008 R2)

Thank you,

Nicolas Desgroseilliers Says:

Wow! Still didn't get any reply on this question... Would someone be kind enough to answer me? Especially Ahmed Nabil...

Ahmed Nabil Says:

What is the type if your VM disk. From inside VM check computer Management, is it Basic or Dynamic ?

Manuel Capela Says:

Hello
I had the some problem, my configuration is : DPM 2012 SP1 and windows 2012 R2 Server with 5 VM's.
that VM come from a 2008 R2 server, so, i had installed the integration services in all VMs in 2012 R2 Server, and see the protection groups in DPM, now i see the Online Backup.

thanks

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