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backupquestions
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A few questions

Post by backupquestions » Dec 02, 2019 4:08 pm

1. Has Vmware provided any more update on the supposed patches to fix the latest CBT issue after reverting vm to snapshot? This was posted here maybe a couple months ago and in a specific scenario I guess after revert to snap you can get corrupt return from * when querying cbt in veeam etc.

2. One of the things Gostev said here was that using Veeam quick roll back feature was better than using snapshots since it didn't suffer from this issue. I found myself that after configuring an alarm in vcenter to let me know when a vm has been reverted to snapshot, that Veeam triggers the same alarm when using veeam's quick rollback feature. So it seems to me that from watching it all, that all Veeam does is restore a snapshot file and attach it to the VM, and then tell esxi/vcenter to "revert to snapshot" in the same api command that a normal snapshot revert is done. So to me this might mean that the problem is no better off by using the Veeam quick rollback feature, and is much slower to use altogether than just taking a vmware snapshot and reverting to it if needed. I would like explanation on whether it is safer at the moment to use quick rollback or not.. If it just uses built in snap revert then will this be changed down the road?

3. On a REFS repository, lets say I have 75TB total space available and I've got several synthetic fulls, so the space used is only 25TB out of the 75TB possible. Now lets say down the road that I have a corrupt backup and I want to take a new active full. So now I will require another 25TB or so as this is the true space of one full. So now I am at 50TB. My question is, in time, with no more active fulls and continued synthetic fulls only, will this redundant 25TB of blocks be deleted and I will eventually end back up with 25TB used? The space savings is a huge benefit for REFS and if forced to take active full I lose a lot of it so I am hoping it will remove the old blocks that make up the original active full from long ago...

Thanks! Looking forward to V10

Andreas Neufert
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Re: A few questions

Post by Andreas Neufert » Dec 02, 2019 4:17 pm

For 1. VMware shared with us that express patches will be released this year. You can monitor here: https://kb.vmware.com/s/article/2143832

foggy
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Re: A few questions

Post by foggy » Dec 03, 2019 6:02 pm

For 2. Quick Rollback isn't just a snapshot revert. The reason why you see such behavior is that Quick Rollback creates a protective VM snapshot, which is then reverted triggering the corresponding alarm. Actually the same happens in case of full VM restore as well.

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Re: A few questions

Post by foggy » Dec 03, 2019 6:07 pm

For 3. With time, the new backup chain (started with the new active full) will reach the retention configured in the job and the older part of the chain (everything prior to that full) will be deleted.

backupquestions
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Re: A few questions

Post by backupquestions » Dec 03, 2019 9:39 pm 1 person likes this post

Andreas and Foggy,

Thank you for the answers!

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