We have Exchange 2007 with a local CCR cluster and SCR to a remote location. We are using Netbackup 6.5.4 and backing up the passive node. So about 2 weeks ago I upgraded our Exch servers to SP3. Everything looked good, backup were running and showing complete. The SG were showing current backup dates. Well we were not checking the transaction log disk sizes and had no idea the log folders were going every day until SCOM started alerting on low disk space. When I checked the drives the logs dated back to the night I did the upgrade. Started looking at the application events and backup logs on the servers and everything seemed normal. What I did not find were any events about the logs being truncated. The check points on the databases show the last backup date so as far as Exchange was concerned I did a successful backup, but it did not delete the log files. After some searching I finally found a posting in a Exchange Technet forum that talks about what I had going on. It appears SP3 introduced a bug that if you performed backups on the passive node, the VSS replication would not kick off the log truncation. Right now the only work around is to backup your active nodes.
I have not seen anything on the list about this so I thought I would post it for those that have upgraded or are thinking of upgrading. I could not find a official KB about it, but I was able to backup the active node and all the logs went away. http://social.technet.microsoft.com/Forums/en-US/exchangesoftwareupdate/thread/519a6d38-6096-4d38-8b11-682ca6e70622
