A few months ago, my organization's Exchange Server 5.5 server was running low on disk space. We were planning to get a new server, but in the meantime I needed to gain some space on the volume where the Information Store (IS) resided. A manual defrag of the IS was overdue, so I decided to perform one.
Unfortunately, I didn't have enough space left on any of the server's partitions to perform a manual defrag on each of the databases (priv.edb and pub.edb). So, I performed a remote defrag on the databases, using disks on another machine that had enough space to complete the operation.
First, I stopped all the Exchange services on the server. I performed a full offline backup with the verify option. Then, I mapped a network drive on the remote machine. I copied the eseutil.exe, ese.dll, priv.edb, and pub.edb files from the Exchange server to the newly mapped network drive. I then ran the command eseutil.exe /d priv.edb on the remote machine to which the files copied. After the manual defrag finished on both databases, I copied the databases back to their original location on the Exchange server. I performed another backup with the verify option. And finally, I restarted the Exchange services on the server.
At this point you can verify the databases' sizes and determine how much space you gained from the manual defrag. If you decide to perform a remote defrag as I did, keep in mind that the process is time-consuming. How long it will take depends on the size of your databases and the processing power of the machine performing the defrag. My priv.edb database was 9.8GB, and my pub.edb database was 3.6GB. The defrag took 4 hours.