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I have full backup running at 6am on Sunday. Differential backup running at 6am everyday. Log backup running every hour.

There is also a Snapshot backup running at 3pm everyday. This is not a copy only backup.

Will the above snapshot backup break the restore chain?

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    This snapshot backup is taken by the SAN disk tool. This is seen in the backupset table in sql sever. Is_snapshot=1
    – variable
    Sep 28 at 12:06
  • 1
    Ok, that's typically called a "volume snapshot" or VSS backup. Sep 28 at 12:55
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Other types of backups shouldn't break the restore chain unless they are specifically configured in a way to do so. For example, I just ran into this issue with Veeam and it managing my Transaction Logs externally which was stepping on my maintenance plan I had running to backup the Transactions Logs internally. You can find more information about that in this StackExchange answer.

Long story short, Veeam has an option (stupidly) to blatantly delete the Transaction Logs, which was how a former member of our infrastructure team setup Veeam. This was breaking the restore chain for me. Turning off that setting was the fix, especially since I had maintenance plans natively managing my backups in SQL Server.

Also, why are you taking a Differential Backup at the same time as your Full Backup? Differential Backups are meant to capture the differences since the last Full Backup (or since the last Differential Backup). You'd be better off doing that later on, like mid-day, or hourly if you want to switch your Transaction Log Backups to be more frequently too.

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A snapshot backup can break your diff backup "chain". (It will never by itself affect log backups unless it does something ...bad like what J.D. mentions.)

Whether or not it affects your differential backup depends on whether it is produced in a way so that SQL Server considers it to be a copy only backup or not. A very old version of Veeam, for instance, didn't do that so it wasn't possible to do differential backup if you used Veeam. This was a long time ago, and they subsequently changed that so the snapshot was produced in a "copy only manner".

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