This was a problem for a customer of mine recently – Information Store wouldn’t backup after they exceeded the 16GB limit and we did an offline defrag ‘eseutil /d’. It would do a partial backup and then fail.
In the event log we were getting:
Event ID: 217
Error -4001 During backup of a database location. The database will be unable to restore.
Prior to the offline defrag the Information Store was backing up fine. The customer has Exchange 2003 SP1. The answer is a hotfix from Microsoft which is incorporated in SP2 however once you have this issue just upgrading to Exchange SP2 will not fix it.
Here’s the Microsoft link which explains how to fix the issue. It’s quite straight forward – obtain the hotfix (we have it if required) and run a taskkill to stop the store process and force a recovery on reboot.