Is It Possible To Determine Snapshots Reliability and Recovery Time?

  • 18 January 2022
  • 2 replies

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I am aware that in snapshot entity details there is a column that tells you if the recovery status is “Recoverable”, but is this enough to be sure it will work if we use it? Also, what exactly happens if App Consistency is set as False?

About recovery time, is it the same for every VM no matter the size of it? Or does it actually depend of how big/small the VM is? If the latter, is it possible to have an estimate recovery time?


Best answer by mikkisse 19 January 2022, 10:19

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Userlevel 4
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Basic snapshot without app consistency (сrash-consistent) = VM, which power was cut off (hard reset) at snapshot creation time. Applications and OS were not aware of the backup procedure.

In crash-consistent snapshots, there is no guarantee that OS and applications/DBs will boot successfully, it’s easy to face with something like fscheck, inconsistent db, and so on, but it’s happened not often in my case and most of the time everything is booting successfully.

So it’s gonna be good to restore something on regular basis just for a test.

Userlevel 2
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Restoring a snapshot should be the same amount of time for any size as it’s just a pointer really to the data. You could always shut down a VM, take a snapshot then turn it back on and you know the snapshot will be in a safe state (i.e. not crash consistent)