Hello,

I have a client who has over 100 GB of log files. Turns out circular logging wasn't enabled. Wanted to know if there are any repercussions to deleting older log files now that circular logging is enabled.

Thanks In Advance,

Well a few things

1. Why are you leaving Circular logging on?  Doing so will limit your recoverability

2. If you are backing up the database regularly the logs will get truncated with each successful backup so that would be the first thing I would look at in terms of maintaining recoverabilty and keeping your logs under control

3. Circular logging still generates logs so you wouldn't want to wholesale delete all logs, however if the logs are exceptionally old & you don't want to keep the logs that are clearly NOT part of the circular logging log set then yes you can delete them

4. If you want to be super safe about log deletion then I would

A: Dismount the databases

B: IF the logs are in a separate path from the databases then rename that log path to OLD_Pathname and make a new folder identical to the original log path folder name.  Then start the databases and you should only see a few logs.  Once everything is running correctly delete the OLD_pathname folder

C: if the EDB and logs are within the same folder then since all logs are committed to DB's when properly dismounted you could just delete all the .LOG files and then remount

GreenTech,

it's Exchange Backup what's clearing the log files, circular logging is not always a good answer to your problem.

First make sure your exchange is backed up properly.

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Jan

If I am correct when you enable circular logging you need to restart your IS for it to take effect. When it does it will automatically purge your logs. But like everyone said you need to find out what's the cause of your logs backing up. Usually, it's a backup related issue - you either aren't backing up Exchange, your backup solution is not exchange aware or you are using incremental backups and don't run (or don't run frequently enough) full backups.

Good points Ziv, however part of the process for changing circular logging will tell you that it has to dismount and then remount the effected stores, however the IS service should not need to be restarted as that would dismount all stores instead of just the effected stores being switched to circular logging

That's a good point - manually dismounting/remounting the DBs is a less intrusive procedure.

Hi,

To understand circular Logging better, I recommend this blog.

http://blogs.technet.com/b/scottschnoll/archive/2011/06/27/circular-logging-and-mailbox-database-copies.aspx

Restrictions of circular logging in Backup and restore concepts for Exchange 2013

1. If enabled during the backup operation or the recovery operation, you cannot restore individual databases.
2. Only point-in-time recovery operations are possible. When circular logging is enabled, you can delete transaction logs in the same directory when a database is restored, although those logs might be part of a different Exchange 2013 database.
3. You cannot perform incremental or differential backup operations.

Best Regards.

Everything is good now. Exchange was using a Windows backup and the admin password on the account was changed. After putting in the new password I was able to run the back up and it cleared out the logs. Thanks for the help everybody.

Excellent, thanks for the update