Microsoft Exchange 2007 to 2010 mailbox move times / statistics

Throughout all the years I’ve been working with Microsoft Exchange server migrations whether it’s for 2003, 2007, 2010 or the current 2013 version, clients tend to ask me how long I expect their mailboxes to be moved and the answer as most know is “it depends”. 

The first consideration with mailbox moves is that the Exchange 2010 CAS server’s Mailbox Replication Service (MRS) actually throttles / controls the amount of mailboxes are allowed to be moved concurrently.  The default settings can be found on your CAS server in the following config file:

C:Program FilesMicrosoftExchange ServerV14BinMSExchangeMailboxReplication.exe.config

Reference article:

Throttling the Mailbox Replication Service
http://technet.microsoft.com/en-us/library/ff963524.aspx

These values can be changed directly in the config file depending on the environment and whether your existing hardware can sustain and/or deliver the extra resources the move operations require.

The second consideration is the contents of the mailbox where you may have some mailboxes with a lot of small messages and others with few messages but large attachments.  I won’t rewrite what Microsoft already has documented in plenty of their KBs so I’ll simply quote the following:

One 4-GB mailbox with 400 items, each with 10 megabytes (MB) of attachments, will migrate faster than one 4-GB mailbox with 100,000 smaller items.

Factors that affect Exchange Online migration performance
http://technet.microsoft.com/en-us/library/jj204570.aspx

The third consideration is the underlying infrastructure such as the server, network and storage hosting Microsoft Exchange.

With the above in mind, I took the time to document the mailbox move statistics for one of the last migrations I had to do for a client from their Exchange 2007 to 2010 and would like to include it into this blog post so I have something to reference to in the future: