Monday, July 7, 2008


The questions below are very generic and ask many times for exchange administrators. I have decided to share one of my post on with you guys here.


What does moving mailboxes to a new store due to Single instance of attachments? I feel my store will grow 20% if I do this.
----Yes breaking the DB into smaller DB will cause SIS to break, but remember having 65GIG one huge mail DB is not efficient for the exchange server, in my opinion. Exchange utilizes what Microsoft terms a single-instance message store. This single-instance message store works on a per database basis. If you break 65GIG into 15 GIG 4 databases (last one is 18 gigs) it will be much easier for exchange to deal with these smaller databases versus one big database, your performance will increase and backup will be happier.

---What is this SIS? It is shared message storage if you would think so, Exchange stores copy of message and creates pointer to multiple mailboxes within the same mail store. If a message is sent to one recipient, and if the message is copied to 20 other recipients who reside in the same mailbox store, Exchange Server maintains only one copy of the message in its database. Exchange Server then creates pointers

If a message is sent to one recipient, and if the message is copied to 20 other recipients who reside in the same mailbox store, Exchange Server maintains only one copy of the message in its database. Exchange Server then creates pointers.

These pointers link both the original recipient
and the 20 additional recipients to the original message. If the original recipient and the 20 additional recipients are moved to another mailbox store, only one copy of the message is maintained in the new mailbox store.

The new mailbox store can be on another server
in the same site or in an administrative group. If the server is in another site, single-instance storage is retained only if you use the Move Mailbox Wizard in Microsoft Exchange Server 2003 Service Pack 1 (SP1) or later versions.

The Exchange Server 2003 SP1 Move Mailbox wizard
introduced a new Cross Administrative Group Move feature that lets you move mailboxes across administrative groups.


I have a Mailbox store of 65GB with a stm of 17GB so 83GB total. my 1221 says i can recover 18 Gbs although I expect to grow internally with new users and have implemented a 3rd party archiver called Sunbelt Exchange Archiver which replaces single instance at that point.

----65 Gig database is too big for exchange to handle (generally speaking),
you have exchange enterprise version you should not let your mail DB to grow this big, this is telling me, there is poor planning in the design exist in your exchange environment
, assuming you are not maxed out with all available databases, and not even utilizing them, why?????

The simple rule is the smaller the database, the happier the Exchange will be (your backup, performance as well)

I would implement the design as below, and distribute the mail boxes equally ( you want to keep a mail store empty, couple so that you will never ever have to use ESEUTIL, again simply as moveing the mailboxes around in the night and delete the ones getting polluted with the white space).


  • SG1-MB1
  • SG1-MB2
  • SG1-MB3
  • SG1-MB4
  • PF1


  • SG2-MB1
  • SG2-MB2
  • SG2-MB3
  • SG2-MB4
  • SG2-MB5 (empty, use for maintenance)


  • SG3-MB1
  • SG3-MB2
  • SG3-MB3
  • SG3-MB4
  • SG3-MB5 (empty, use for maintenance)


  • SG4-MB1
  • SG4-MB2
  • SG4-MB3
  • SG4-MB4
  • SG4-MB5 (empty, use for maintenance)

The problem with any archiving software is, when you run the third party utility, it will go to exchange and index all the mail you specified within the time range and leave some short cut in the user mailbox. The idea is great the user won't even understand where the mail is, they will click on the shortcut icon and that time mail data (most likely is going to be sitting on some type of SAN, environment will come back to exchange mail store, so that the user can see it. When you index 63 gig mail data, the size of the database won't change; you will end up having WHITE SPACE, therefore you will have to keep some empty mail stores to move user mailboxes and delete the one with white space, don't even bother with ESEUTIL, waste of time.


So do I create a new Storage group ( I have enterprise) or Do I just create a new Store in the First Storage group? Like Mailbox store current To New Mailbox store Or is it better to create a new storage group\Like First Storage group Mailbox Store to Second Storage Group Mailbox Store

--I have already answered this question, the design has mentioned above is true for exchange 2003, the new recommended implementation is 1SG + one DB for exchange 2007.


Oz Ozugurlu

MVP (Exchange)


MCSE 2003, M+, S+, MCDST

Security+, Project +, Server +



Josh Maher said...

This is great for Exchange 2003, but I would be curious to know your opinion on the same issue for Exchange 2007??

Oz Ozugurlu said...

Josh, first of all thanks for reading the post. Have a look to link below if you have not done it so

I will write soon, artickle in regards to some design senarios with exchange 2007 and will post it here on my blog