RE: migrating accounts from Exch 2000 to REMOTE Exch 2003

  • From: "William Holmes" <wtholmes@xxxxxxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Mon, 10 Jan 2005 13:09:52 -0500


That depends. If you have a bunch of attachments and they have been using
single instance store and you export the mailboxes with exmerge you will get
a copy of each attachment for each recipient.  That is to say if previously
20 users who are hosted on the same exchange database all received a
particular message with a 3 megabyte attachment the total storage for that
attachment on the old database will be 3 megabytes.  However when you use
exmerge to export the data you will get 20 copies of the attachment. One for
each exported account. When the maiboxes are imported back to your new
exchange server you will need 60 Gbytes to store the attachments. Exmerge
does not preserve single instance storage. 

So to answer your question yes you may need additional storage for your

On the other hand the source database could have a lot unused space. Remember
databases files don't shrink when messages are deleted. The space will be
re-used by exchange but as far as the size of the database file goes it does
not necessarily indicate the size of the mailboxes in it.


-----Original Message-----
From: A. M. Salim [mailto:msalim@xxxxxxxxxxxx] 
Sent: Monday, January 10, 2005 10:45 AM
To: [ExchangeList]
Subject: [exchangelist] RE: migrating accounts from Exch 2000 to REMOTE Exch


Another migration question:  can I safely assume that the final mailbox sizes
(store sizes) will be about the same on the new Exchange 2003 that I had on
the old Exchange 2000, assuming I am migrating all content and not adding any
new content for now?  Is there any reason the store size on the new Exch2003
will be larger than the old store size on the old Exchange 2000?

The current store size is around 10GB on the old Exchange 2000 server and I
would hate to find that the new store size now wants to be 18GB for the same
data on the new Exchange 2003 server! (especially since there is a 16GB


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