adding and extra Exchange DB to exchange server 2010  v 14.02

Posted on 2015-02-13
Medium Priority
Last Modified: 2015-02-24
I want to add a new data-store to our current 2010 exchange server.
This is to migrate some users who we don't need to backup from the main DB.
We also want to offline defrag the main DB and getting old users off it should make it faster.
The current size of the mail store is 255GB.  

Are there any issues I should be aware of?
When I migrate a mailbox to the new DB does it automatically defrag?
When I migrate a mailbox to the new DB does that space get freed up in the old DB?
Question by:wannabecraig
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R--R earned 500 total points
ID: 40607516
The database will not be automatically defrag and the space will not be freed up until you defrag the database.
why do you want to defrag the database if you are going to move the mailboxes to new database.

For better management of the database I recommend you to create the 3 to 4 database which should be smaller and easy to manage.
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VB ITS earned 500 total points
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With a database size of 255GB, you will want to look at splitting up the mailboxes into separate databases or else you may find recovery times will be very long.

Exchange 2010 Standard gives you a limit of 5 mailbox databases so why not make use of it? If you have the disks you can place the databases on different drives for improved performance.

The answers to your question above are both no. You must perform an offline defrag if you want to reclaim disk space. Because offline defrags can take so long (especially on larger databases), it's often easier to just create a new database and move all the mailboxes to the new database.

The only sort of online "automatic defrag" that occurs is the online database maintenance which runs on a nightly basis by default. This online database maintenance performs a number of tasks. If you'd like to find out more details on what exactly occurs you can read this article which covers it in depth: http://blogs.technet.com/b/exchange/archive/2011/12/14/database-maintenance-in-exchange-2010.aspx
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by:Peter Hutchison
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Exchange does do an online defrag, this moves data around to free up space within the database, but does not free up disk space or make the database smaller. You need to do an offline defrag with ESEUTIL tool.

Also, a database of 255 GB is too big, you should keep them under 100GB per database. A large DB reduces performance due to high IOPS.
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by:Adam Farage
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ID: 40607663
Exchange runs off ESE, which already does a 24x7 online maintenance on the database. This online maintenance is a throttled service, so if resources are not available it will simply throw a MAPI flag on the database and continue when it does have resources.

With that said this does a number of tasks to optimize the database, but does not actually clean up whitespace. ESEUTIL /D (offline defrag) will not increase the time it takes to move a mailbox, nor is it even recommended anymore. It is recommended to create a new mailbox database and move all mailboxes there when you need to clean up whitespace, as this is a safer alternative that will replicate from the source database (the original host) to the target database (the new one you just created) thus removing whitespace and typically resolving any corruption issues.

I somewhat agree with the others above about keeping multiple databases, but since you are most likely running Microsoft Exchange 2010 Standard you have a limit of 5 databases. I would recommend a few things:

1) If the business allows place in quotas to help limit the size and growth of these mailboxes. The other reason to place in quota is if the mailbox somehow becomes corrupt you have a way of stopping a mailbox from growing out of control (which I have seen a mailbox grow upwards to 400GB before.. a single mailbox)
2) Split the mailboxes across 4 databases. 255GB is NOT too big. For a single instance environment (e.g: NOT running a DAG) then 250 is the recommend maximum. Splitting it across will help with RPO / RTO (recovery point / time objectives) as it will be easier to restore and run ESEUTIL /R or /P from if ever needed, but its something to keep in mind.

If you utilize 4 of the 5 databases that come with Standard, you always have a staging database for new users and if you need to move users around due to the old source database having to much whitespace (and you need to clean up whitespace).


Author Comment

ID: 40611928
Thanks All,

I have created a service DB that I dont need to backup, we can move old users here etc.
I've also created a main ebd where I intend moving the main users for the business (about 50).  I will back this up.
The original ebd should then be pretty empty.
Then I can defrag the original ebd and move the service users there, then just leave the service db there for utility. (remove backup)

Before moving users, should I be asking them to clean up their mailbox?
Also, should I reduce/remove the retention limit on the existing ebd so users are not bringing that space across with them to the new ebd?
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Expert Comment

ID: 40612178
It may be easier to just create a new blank database for the service accounts and then move them to this new database. No use taking the database offline and waiting a long time to do a defrag to reclaim disk space.

Before moving users, should I be asking them to clean up their mailbox?
Yes, if this is possible then definitely recommend it. You may also want to implement mailbox quotas for the entire database but that decision is really up to you.

Author Comment

ID: 40626582
I notice when moving DBs the logfiles (I think they are ayway) are quite big.
Well they#re 1MB but there are many of them. Shold these be here? do they clear down after backup?

Author Comment

ID: 40626856
Also, one of the DBs I created on the advice above is a service MB which I don't want backed up.
How can I clear down the transaction logs if I'm not backing it up?

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