Circular logging Log file cleanup - What's the trigger?
I have circular logging enabled on Exchange 2007 SP1 storage groups which are backed up each weekday with a full backup.Thevolume with the log file has around 20Gb of space and we typically have about 2Gb of traffic per week, so log space is ample for normal circumstances.When I migrate mailboxes from Exchange 2003 to Exchange 2007 the log folder has a greate many log files created that do not go away when the move operation has completed. Once I've moved around 20Gb worth of mailboxes the databases dismount and I have to recover with ESEUTIL /r /t command. Which works but very messy. (I have SCR enabled and I have to reseed those each time this happens. SCR log shipping delay should not cause the log files to hang around this long either, they are shipped over the same Gigbit LAN the mailboxes are copied).My question is, what is the trigger to delete log files when circular logging is enabled? The reason for enabling circular logging to to avoid this exact problem while mailboxes are migrated. I expected once there are no current transactions that unneeded log files would be deleted at that time. I've even tried dismount/mount between move operations and that does not delete the log files either.Cheers,Mark.
September 27th, 2009 6:15am

Hi Mark,even if you enable the circular login, it wil not straight away delete the log files. This is i think is a two step process1. Logs getting committed to Database.2. Then log files getting purge.Step 1 will only happen if your store.exe is free and can take the logs files. Just check if the log files has been committed to the DB (check for event logs). Why dont you go ahead with a full Backup and your Logs will automaticlly get purged.Raj
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September 27th, 2009 9:35am

update:Now that I'm watching the log folder diligently the circular loggin is working as expected. It never creates more than 200 log files and they dissapear once the move operation has completed.So how did it create over 20,000 log files in order to cause the problem I had earlier?
September 27th, 2009 11:16am

Moving of mail boxes will always create lot of log files. So in case you plan a move mail box , please make sure you have ample of free space on the log files partition and this is not an issue. Its normal behaviour.Raj
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September 27th, 2009 11:46am

update:Now that I'm watching the log folder diligently the circular loggin is working as expected. It never creates more than 200 log files and they dissapear once the move operation has completed.So how did it create over 20,000 log files in order to cause the problem I had earlier? The trans logs wont be discarded/re-used until the checkpoint has been advanced. In situations where a large amount of transaction logs are created, it may take some time before that happens.
September 27th, 2009 6:29pm

I was moving mailboxes 20 at a time and monitoring the log files, initally the log files did get cleaned up very shortly after the move operation finished.On the last batch I got impatient as I was running out of time (it was last Sunday evening) and my maintenance window was coming to a close. So I started the last batch of 20 while the previous operation was still tranferring the last large mailbox from that batch.Doing that seemed to change the circular loggin behaviour, I then ended up with 1500 log files and they did not get cleaed up quickly after the move had finished. Not a problem in this case as I was now finished. Yay!
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September 28th, 2009 6:28am

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