Exchange 2010 Database way too big for size of organization

Problem:  I’m managing an Exchange 2010 server with roughly 210 mailboxes.  Most of which aren’t very big only a few hundred MBs or so and have them setup within two databases for organizational reasons.   The main DB has 157 mailboxes and was a whopping 346GB!!! Which is way too big and is making my backups take up to 24 hours to backup the whole DB, along with the mailboxes and other files.

Solution:  After much reading, I found out that the problem had to do with two things:  1.  Most of these mailboxes were migrated from an Exchange 2003 server and there has been known cases that the Exchange 2010 server DB can be a little bloated.  2.  I then created a new DB and moved about 50 mailboxes to that DB which created white space within it.  

Some of my options were to defrag my Exchange database using Esutil but from what I gather, it is not recommended by Microsoft and I have to take the DB offline to do it.   My other option and the best one was to create a new Exchange database and move all my mailboxes to there.   I did that and the size of my new database is about 60GB!  Much better than the 340GB before. 

*Note – When a mailbox is being moved, it will be unavailable during that time.  The length depends on the size of the mailbox. Keep that in mind when moving large mailboxes.   Also, make sure you do a full backup of the database after the move is done.


4.22.13:  I had my old database dismounted for the entire weekend before I removed it.  Just in case…  So today I attempted to remove the old database and got the following error:

Exchange 2013 Database Removal Error: “This mailbox database contains one or more mailboxes”

Below is a great article on how to address this problem so you can safely remove the database.

2 thoughts on “Exchange 2010 Database way too big for size of organization

  1. I seem to have similar problem, my db shows 400GB, but running mailbox statistics shows my users took up only 159GB space. How long did it take you to move your db and mailboxes to the new database?

  2. For me it was about 5 hours total. I broke it up into smaller groups because I was making some mailboxes unavailable. Just to give you an idea, it took 4 hours to move one mailbox that was 9GB! I should also note that when you do a mailbox move, the server will only process two requests at a time and leave the rest pending. That is a bottle neck of sorts but I’m thinking it’s to make sure the integrity of the mailbox is kept.
    Since your new DB is a bit bigger(about double of my new one), I’m thinking that it will take at least 5 or 6 hours; depending on your servers specs.

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