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mkaec
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CBT and AVHDX File from VSS

Post by mkaec » Apr 21, 2016 3:10 pm

Host: Windows Server 2012 R2

When a backup is running, I notice that AVDX files are created. Then after the backup completes, the AVHDX files merge in and are removed.

I have seen that if one backup job causes the creation of AVHDX files and another backup job of the VM starts, the merge will pause and new AVHDX files are created. After the second backup job completes, both sets of AVHDX files merge into the main VHDX files and are removed.

My question is, when the second backup job starts, does this cause a full scan to occur instead of using CBT to detect the changed blocks? From the documentation, I gather that if I manually create a checkpoint, CBT is no longer used. I'm wondering if the existence of the auto-created VHDX files causes similar behavior.

Vitaliy S.
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Re: CBT and AVHDX File from VSS

Post by Vitaliy S. » Apr 21, 2016 6:54 pm

Hi Marc,

CBT is tracked within each job separately, so it shouldn't cause issues, you can check that by processed data counter mentioned in each backup job session.

Thanks!

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