We had faced the same issue earlier & at that time we have upgraded the exchange 2007 to Sp2. Log files were getting purged by running VSS full backup on the log files volume. This issue has come up again after the server had faced a abrupt shutdown. We were getting VSS writer error on the application log which stopped after we remove the .bak SID entry from the registry. backup is running fully without any problem but log files are not getting purged now.

Hi, 1. Please post the detail location of the registry here. 2. Please post the detail error information here. 3. Please check if you have enable circular logging. 4. Please let me know if you have LCR or CCR environment. 5. Please let me the operation system of the Exchange Servers. Besides, please try to follow the steps in article below to troubleshoot the issue. Troubleshooting Exchange 2007 VSS Backups http://msexchangeteam.com/archive/2008/08/25/449684.aspx Regards, Xiu

It might be a problem in the Sequence of the Log Files. Try to Dismount the Database that you are trying to purge. Move all the Log Files to another Location. Then mount the Database back again. This will create a new sequence of Log Files. Now check with the Backup and see if this works. Note :- Since there was a Shut Down then there could be a possible issue with Log files being corrupt.Ashwin Raj

We had log files & storage groups on different volumes & I was selecting only the log files volume for backup. I did a complete backup of the exchange server & log files got purged.