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LMS
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Need some clarification on VM backup on 2012 R2 HV host

Post by LMS » Mar 25, 2018 9:10 am

Hi

We found in KB article saying while taking VM backup on 2012 R2 it creates 2 snapshots (backup checkpoint of VM & auto-recovery checkpoint), but while taking backup of VMs we didn't find this .avhdx neither with the VM settings nor with virtual disks location. All the VMs are running on Hyper V 2012 R2 clustered hosts CSVs (the VMs are not clustered). Please clarify

Thanks in advance

LMS
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Re: Need some clarification on VM backup on 2012 R2 HV host

Post by LMS » Mar 25, 2018 11:12 am

Also not getting the idea behind creating internal snapshot after cretaing backup checkpoint & auto-recovery checkpoint and passing this internal snapshot to HV-IC.

Mike Resseler
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Re: Need some clarification on VM backup on 2012 R2 HV host

Post by Mike Resseler » Mar 26, 2018 6:37 am

Hi MS Sunil,

Whenever we create a backup for a 2012 R2 VM (I am believing you are doing online backups?) the hypervisor will create a GUID.avhdx (the GUID is the VM ID). So you won't see nameVM.avhdx but GUID.avhdx. This is the file where all the new writes get written to, and which will be used to perform the merge at the end when the backup is finished.

Right after that, there is indeed a auto-recovery checkpoint GUID-Autorecovery.avhdx. This auto-recovery checkpoint helps to make sure that VM data is consistent during backup.

This is done to mount the auto-recovery checkpoint to the VM, and to roll back the data on the VM to the consistent state.

Hope it helps
Mike

LMS
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Re: Need some clarification on VM backup on 2012 R2 HV host

Post by LMS » Mar 26, 2018 10:09 am

Thank You Mike.

Sorry, still it's not clear to me. We are performing online backups. While running the backup we looked for the GUID.avhdx, but didn't find it either on VM disk folder or didn't saw the refernce to this avhdx in VM property. Theoritically it's clear that it creates a backup checkpoint and all new writes are performing here and this avhdx merges at the end of the backup.

Also the doc says it creates a auto-recovery checkpoint right after the creation of backup checkpoint and then VM VSS takes a internal snapshot and passes it to HV IC. We know both the checkpoints are created by HV VSS after VM applications are quiesced. So how the auto recovery works with 2012 R2 in detail (mounts auto-recovery checkpoint, rolls back data on VM to consistent state, takes external snapshots and merges auto-recovery checkpoint with original VM). To be specific we are not clear with auto-recovery checkpoint - internal snapshot - rolls back data on VM to consistent state.

Can you please clarify it in detail

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Re: Need some clarification on VM backup on 2012 R2 HV host

Post by Mike Resseler » Mar 27, 2018 5:46 am

Hi MS Sunil,

Did you read this? https://helpcenter.veeam.com/docs/backu ... =95#2012r2
That is the entire workflow that we do when we do an online backup for server 2012 R2. Does this makes sense?

Thanks
Mike

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Re: Need some clarification on VM backup on 2012 R2 HV host

Post by LMS » Mar 27, 2018 1:24 pm

Thank You Mike. My concern is on point 7 (The framework inside the VM takes an internal snapshot using a Microsoft Hyper-V Integration Services Shadow Copy provider in the VM guest OS), is this internal snapshot taken before creating both the checkpoints? If that is the case , then everything is clear.

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