SR migration causes full backup on delta backup job
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I've noticed that whenever I migrate a VM disk from one SR to another that my nightly delta backup performs a full backup for that particular VM. Is this expected behavior and is there a way to prevent it from happening?
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Hi,
This is expected. When you migrate the VDI, a fresh new one is created on the other side, so it's completely different ("consolidated" if you will), and it's impossible to diff it anymore.
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@olivierlambert Does this happen as one step or are there discrete stages? Is there a way to get more visibility into it?
Also, is the migration going directly from SR to SR or is it passing through XO?
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It's happening when you do the migration, once for all. The VHD is generated "from scratch" on destination, by reading the VHD chain on the source and consolidating everything into a single "fresh" VHD.
Migration is between XCP-ng, XO isn't involved in the process at all.
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@olivierlambert I have a related question that I can't seem to find the answer to in the documentation.
If I migrate a VM from local storage on one host to another host but with shared storage, what path does it take? Does the first host send the disk directly to the shared storage and then the memory to the second host?
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Roughly, a snapshot is created and transferred while all new blocks written are mirrored to the destination. When the entire snapshot is created on destination, the VM is frozen few ms to finish consolidating the mirrored blocks into the destination snapshot. And then the memory is transferred.
