April 28, 2009 at 3:37 pm
Hi there,
Here is a odd question for everyone. I know the backup chain starts at the full backup and ends at the following full backup and a new chain begins. Consider this scenario:
12:00 AM Tuesday full backup
12:00 PM Tuesday Transaction log backup
12:00 AM Wednesday full backup (fails)
12:00 PM Wednesday transaction log backup
If the Wednesday full backup fails, can the chain created from the Tuesday full backup carry over to the transaction log backup completed on Wednesday?
thank you
April 28, 2009 at 9:53 pm
Your definition of when the backup chain ends is not correct. A full backup does not end the chain. The chain is terminated when there is a discontinuity in logging (changing to simple recovery will do this) or if you are missing one of the transaction log backup files.
In your example, you can roll forward from the Tuesday full backup past the failed Wed full backup using the log backups from Tue and Wed.
April 29, 2009 at 12:44 am
Full backups do not truncate the transaction log. Only log backups do that. The only things that break a log chain are backup ... with truncate only and a switch to simple recovery
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
May 1, 2009 at 11:54 am
And this is why do DO NOT delete old backups before ensuring the new one is complete and successful.
Follow me on Twitter: http://www.twitter.com/way0utwest
Forum Etiquette: How to post data/code on a forum to get the best help
My Blog: www.voiceofthedba.com
Viewing 4 posts - 1 through 3 (of 3 total)
You must be logged in to reply to this topic. Login to reply