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Daveyd
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Veeam integrated VSS Backups and SQL 2008

Post by Daveyd »

I am currently using Veeam 4.11 and one of my VMs in one of my backup jobs is a 2008 server running SQL 2008 SP1. I have enabled Veeam VSS integration. Every night when the Veeam backup occurs of that VM, I get an alert email that is generated from an application that uses the database on the VM that I am backing up, that the database server is offline. Is this to be expected with using Veeam VSS integration? Would the database server be inacessible when Veeam is quiescing the database/VM?

Gostev
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Re: Veeam integrated VSS Backups and SQL 2008

Post by Gostev »

Hello Dave, this is a result of Microsoft SQL Server VSS writer quiescing the database. To make this happen, SQL VSS writer needs to stop SQL from accepting new transactions for a brief moment, let the current transactions complete, and report back to Windows VSS that the application is frozen, at which point Veeam creates VMware snapshot of this VM. We are talking about a few seconds here.

So, SQL not available for client apps for a brief moment is normal. Most typically however, well written client apps will not issue warnings unless SQL is not available for extended periods of time, instead retrying the connection first a few times to ensure it is not intermittent network or SQL overload issue (instead of assuming right away that the server is offline) - which are both quite common issues in large networks. So, I would say it is the app behavior which is not "normal" here (unless SQL is really unavailable for minutes, of course).

Daveyd
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Re: Veeam integrated VSS Backups and SQL 2008

Post by Daveyd »

Gostev, that looks to be the case. Looking at the SQL logs from yesterday, I/O is frozen on the database at 12:15:10 and then I/O resumes on the database at 12:15:21. I guess the alert on the application sees that as the DB being "down" which I guess technically it is. Unfortunaetly it is a generic application alert with no customization on my part.

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