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Log backup happening while a full backup is running

ChrisAVWoodChrisAVWood Posts: 361
edited December 19, 2007 5:14PM in SQL Backup Previous Versions
In SQL2000 it would not allow a log backup to happen while a full backup was running. This is now different in SQL2005.

We have just started to use Red Gate SQLBackup and discovered we had scheduled log backups running while scheduled full backups were running too. I found this out because we had MemToLeave memory problems.

I asked a question on the MS NG's about how SQL2005 maintenance plans handled this situation and I was told: -

The log chain always spans full and diff backups as long as the recovery
mode stays in full. That way if you had a corrupt full backup you can always restore the last good full backup and still have the log restores all the way thru. When you take a Full backup there is always a mini log backup included in the Full backup. That is one way they are able to make the backup consistent from the end of the backup not the beginning. As such it has the last LSN that was successfully applied on recovery. So when you restore a log backup it will check the LSN in the log file against the last one applied and act accordingly.

We are running with a Full recovery model. So my question is how does SQLBackup 5.2 handle the situation when a log backup happens while a full backup is taking place?


English DBA living in CANADA


  • Options
    peteypetey Posts: 2,358 New member
    SQL Backup doesn't 'pull' the backup data itself. It relies on SQL Server to do that. If SQL 2005 is able to pass transaction log backup data to SQL Backup while a full database backup is running in parallel, then SQL Backup will just process the data as usual.

    Perhaps this documentwill make things clearer.
    Peter Yeoh
    SQL Backup Consultant Developer
    Associate, Yohz Software
    Beyond compression - SQL Backup goodies under the hood, updated for version 8
  • Options
    Thats just the information that I needed.


    English DBA living in CANADA
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