A few weeks ago I was at an event where someone came up and asked me if it's bad to perform transaction log backups while full/differential backups are running.
I said I couldn't come up with any reason why it would be "bad", but it's important to note that:
- VLFs will not be marked as inactive by a log backup while a full/diff backup is running
- There can be increased I/O impact due to multiple backup processes running concurrently
They then explained that their supervisor has handed down an edict that no transaction log backups can run while full backups are running. They asked if I could explain my thoughts to their supervisor, who was also present at the event. I tried. They blew me off and said that "I'm never going to need to use a transaction log backup that was taken while a full or differential backup was running, so why bother creating them?"
I thought for a second, and my replies at this point were:
- The longer you wait in-between transaction log backups, the longer they will take to create
- You may find yourself needing those log backups if you have to do a point-in-time restore to a time that a full or differential backup was running.
The supervisor told me I was just "making stuff up." I said I'm sorry they felt that way, and left it at that.
This exchange left me feeling absolutely certain that I never want to work for that person. Ever. It also left me curious as to if I was really right or not.
Does anyone have any comments either for or against my replies in this situation? I'd be interested in hearing any and all input.
Microsoft Certified Master: SQL Server 2008
Blog: The Outer Join