Exchange 2010 introduced the ability to move your personal archive mailbox to a separate mailbox database. This was a common request due to the limitations in Exchange 2010 RTM where the personal archive mailbox would be housed on the same database as the user mailbox.  This would of course limit the ability to use a tiered storage model.

In order to move the personal archive mailbox, we would need to ensure both the user mailbox as well as the archive mailbox are on SP1.  So if you are in a multi-server environment where some mailbox servers are RTM and SP1 and you have moved the user to SP1 and want to then split off the personal archive mailbox to a separate database, make sure that server that you move the personal archive mailbox to contains SP1. Should you decide to move the mailbox back to RTM, you must move both the user mailbox and the personal archive both to an RTM Server.

So let’s go through two scenarios.  The first, we will move an existing user’s personal archive to a separate database.  The second scenario we will create a new user with a personal archive and have the personal archive live on a separate database.

Important: Please keep in mind that the screenshots below SP1 Beta softwareand even the statement about Microsoft Support are not final as this article is based off of SP1 Beta software and may change by the time Exchange 2010 SP1 ships.

--> The rest is on the website :

http://www.shudnow.net/2010/04/07/exchange-2010-sp1-personal-archive-mailboxes-on-separate-databases/