circular logging

cashew

I understand that when circular logging is enabled after it reaches it 5mb limit the file is purged and a new one is created. Since the file is deleted, does that mean that it's directly written to the database at that time?

royal

No it doesn't mean it's written to the database at that time. It gets written to the database on 2 different conditions. One is that when you shut down the database, all log information gets written to the database to make sure the database is consistent. Also, Exchange will occasionally write from the logs to the database when it feels it is best to to help keep it up to date.

Check out this article:
http://technet.microsoft.com/en-us/library/d42ef860-170b-44fe-94c3-ec68e3b0e0ff.aspx

cashew

So if it's deleted from circular logging and not written directly to the database does this mean circular logging does create multiple log files? Then once these log files are written to the database the files are deleted?

royal

Sorry, I was talking about when not using Circular Logging. When using circular logging, it would have to move the information to the database so it can start re-using the log files.

Here's another article:
http://support.microsoft.com/kb/271987

cashew

As usual IC, you are the man! Thanks

sprkymrk

Circular logging is not recommended as it kills the ability to restore older backups and roll forward. It is used only when disk space issues are critical. Circualr logging does not create multiple log files.

I see the second link by IC explains it all very well, so I'll stop here, and leave my comments above for those who don't like to follow links.