The followingappears in our event log under information: MSExchangeIS (7264) Second Storage Group: Online defragmentation has completed a full pass on database 'D:\Program Files\Microsoft\Exchange Server\Mailbox\Second Storage Group\Public Folder Database.edb', freeing 21 pages. This pass started on 2/25/2009 and ran for a total of 9 seconds, requiring 1 invocations over 1 days. Since the database was created, it has been fully defragmented 78 times over 78 days. I have moved several large mailboxes to another storage group/db and thought I had to dismount and defrag the above storage group/db to show the true size. What I needto knowwith the above happening do I still need to dismount and defrag?Thanks

Online maintenance runs each night and marks whitespace as such, and an offline defragmentation is generally not needed unless you actually want to reduce the size of the database files themselves. The Online defrag does not reduce file size. Look in the Application Log for eventID 1221. This will appear for each database. 1221 shows you how much whitespace is in your database that could be reclaimed by an offline defrag. See here for more detail:http://msexchangeteam.com/archive/2004/07/08/177574.aspxMike Crowley: MCT, MCSE, MCTS, MCITP: Enterprise Administrator / Messaging Administrator

What you need to do is, as Mike said, to check the event 1221 and verify if online maintenance finished successfully. Please see this article