Usually, I run without ciruclar logging and use BEX 9.1 to clear the log files off my Exchange 2003 SP2 clusted instance. Today, however, I've had to turn on circular logging to cope with an out-of-control inbox rule that filled my log volumes and caused the mail store to dismount. Never though about it before, becuase circular logging was not our list of options -- but can I combine ciruclar logging with on-line backup by Veritas?

Circular logging prevents replay of transaction logs in the event of a database restore. Here is how a traditional backup situation would work. Imagine your last full backup was Friday night and today its Monday at 4pm and your database needs to be restored. If you restore the backup from Friday, you can then replay the transaction logs written after the backup, but before the failure. This would allow you to restore your database to almost the exact point it failed. Without the logs, youre stuck with Fridays data, and youve lost everything over the weekend and all morning today. This is traditional logic. There are other ways of dealing with this, such as multiple copies of the database (Exchange 2007+) and 3rd parties have continuous backup solutions as well; both of which mitigate the problem. Its up to you to decide if your configuration BEX 9.1 mitigates this effectively. Mike Crowley | MVP My Blog-- Planet Technologies

I appreciate your response. I think my question is, in a nutshell: will the use of on-line backup against an E2K3SP2 database running ciruclar logging damage the priv.edb file, or will it just do the backup and shrug, saying 'ok, so you had no log files for me to truncate. No big deal.'

How does Backup Exec use circular logging Backup Exec will back up and then delete the committed (post-checkpoint) log files during a full backup job. This manages the log file and provides the protection that is required against hard, soft, and media failures of the exchange server. Performing a full backup of the Microsoft Exchange Server is the preferred way of saving the log files and removing these logs from the disk to utilize the space effectively. src: http://www.symantec.com/business/support/index?page=content&id=TECH5767 Mike Crowley | MVP My Blog -- Planet Technologies

Hi, Here is an article about circular logging and backup you can refer to: http://blogs.technet.com/b/exchange/archive/2010/08/18/exchange-circular-logging-and-vss-backups.aspx Hope it helps. ThanksSophia Xu TechNet Community Support

In Exchange 2010, you have only two backup choices; use VSS or use Exchange 2010 Native Data Protection - DAG plus LAG(s). If you turn circular logging on, and are using VSS backups, then you must turn it off before your next backup or the backup job will fail. If you are not using VSS, and instead are relying on Exchange 2010 Native Data Protection, then you must leave circular logging on; otherwise you log drive will fill up and your databases will go offline. It appears you are using BEX 9.1 & by extension VSS, and not Native Data Protection. You must turn circular logging off before your next backup or your jobs will fail.

In Exchange 2010, you have only two backup choices; use VSS or use Exchange 2010 Native Data Protection - DAG plus LAG(s). If you turn circular logging on, and are using VSS backups, then you must turn it off before your next backup or the backup job will fail. If you are not using VSS, and instead are relying on Exchange 2010 Native Data Protection, then you must leave circular logging on; otherwise you log drive will fill up and your databases will go offline. It appears you are using BEX 9.1 & by extension VSS, and not Native Data Protection. You must turn circular logging off before your next backup or your jobs will fail. This is incorrect. Please see the above link from Symantec. Circular logging does not cause backup jobs to fail. Mike Crowley | MVP My Blog -- Planet Technologies

Well, thanks to you all. It turned out like this: The Trend Micro Virus Scanner reflected which users' messagses were being scanned, and thus were passing through the system at the time of the excess log file generation. The user turned of his inbox rules. The excessive log file generation stopped Circular logging was turned off I returned to normal, on-line backup behavior Case closed.