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Hyper-V backup SQL log behaviour experience ?

Michael_G_Ander
Level 6
Certified

What are peoples experience with SQL log behaviour, when doing a Hyper-V backup of a SQL server with databases in full mode ?

Have already looked at the theoretical stuff which seems to be conflicting as the Hyper-V VSS system is supposed to send a log truncate at successful backup and the SQL writer which does not seems to support log truncate.

 

 

The standard questions: Have you checked: 1) What has changed. 2) The manual 3) If there are any tech notes or VOX posts regarding the issue
5 REPLIES 5

Marianne
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To my knowledge, only NBU for VMware supports 'Application aware' backups.

For Applications and DBs on Hyper-V, regular agent backups should be performed.

 

Yes, I know that is the Veritas stand point. But I am as written interested in peoples real life experiences as the theoretical stuff is conflicting.

My personal suspicion is that the Hyper-V VSS sends the truncate log and that the SQL writer discards it as this writer does not support the log truncate.

The standard questions: Have you checked: 1) What has changed. 2) The manual 3) If there are any tech notes or VOX posts regarding the issue

Michal_Mikulik1
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Hello,

I am not sure I understand this question. Maybe Hyper-V/MS SQL forum is better for this discussion.

However I doubt that Hyper-V VM level snapshot will take care of MS SQL log truncations..

Regards

Michal

So far our testing show the SQL logs are not truncated, at least not with the default settings.

The standard questions: Have you checked: 1) What has changed. 2) The manual 3) If there are any tech notes or VOX posts regarding the issue

Michal_Mikulik1
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Hello,

yes , I think it would be "pretty" bug when Hyper-V snapshots (or any non-SQL snapshots) would truncate SQL transaction logs, thus compromising databases recoverability.

Michal