Optimal Way to size the mailbox database

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MTN User1900

I work for a huge organization which has many departments. I wish to plan the database according to the departments. What would be the optimal way to plan for it?

eg. if I have 10,000 users from 5 departments (each user with 150mb allocation)

1) Should I group them into 5 database with 2000 users' mailbox each or

2) 10 database with 1000 users?

How about a case of 5000 users with 1 GB allocation?

What would be the relationship (in terms of logs, access time and recovery) between the number databases and its' users

Is there a guideline so that we can optimally plan for the distribution of mailboxes in the database, so that DAG performance level is well balanced and LUN storage design nicely craft out.

PS: what is the max number of users I can sequeeze into one database? Is it 10 GB?

Many thanks in advance!


Sean van Osnabrugge


The best way to properly size a new deployment is to profile your existing users.  If you are using Exchange 2003/2007, then you can make use of Exmon to profile your existing users, an excellent guide for Exchange 2003 can be found here: http://www.msexchange.org/tutorials/Microsoft-Exchange-Server-User-Monitor.html

Once you have this information, then you can use this information for sizing along with other variables such as how many mailbox servers, DAGs, mailbox size,  deleted item retention days, etc.

In Exchange 2007, Ross from the Exchange Team published and maintained a calculator which will likely be updated for Exchange 2010 when it is released.  In the meantime, you may manually make these calculations by reading the following: http://technet.microsoft.com/en-us/library/dd346703(EXCHG.140).aspx

Sean | http://seanv.wordpress.com
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