Defragmentation of Exchange Database

Posted on 2013-11-17
Last Modified: 2013-12-09
We have two Exchange Server 2010 SP2 which are members of DAG and contains HUB, Client Access & Mailbox roles. Currently one database  is reaches to 700 GB which causes space issue as well back up issue.

How we can reduce database size...need guidance to overcome this issue.
Question by:sanjayambre
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LVL 37

Expert Comment

ID: 39654689
If you have additional disk space \ disk, then probably u can create new mailbox database and start moving mailboxes there to reduce its size and backup problem as well
Alternatively you can defragment
check below post

Author Comment

ID: 39654814
We started to move mailboxes but database size is remain same due to white space. Is there any calculation how much time will take to defragment database (700 GB).
LVL 37

Expert Comment

ID: 39654825
Basically, you need to create new database and need to move all mailboxes to new databases
Later on original database need to wiped out
This process will recover white space and keep new database compacted.
Also you don't required downtime during mailbox movement probably since you are running Exchange 2010 version
Defragmentation is the process where you take the database offline and this process will take too much time to defragment 700 GB data
Not sure exact time, but may take more than24 HRS
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LVL 63

Assisted Solution

by:Simon Butler (Sembee)
Simon Butler (Sembee) earned 83 total points
ID: 39656351
You cannot defrag a database with a DAG involved.
Therefore your only options are to move the data around. You could break the DAG and then defrag the single copy. You would then have to completely reseed the database. That is going to take some time.

Your best option is to create new databases, completely replacing what you have. Seed those new smaller databases across.

LVL 37

Assisted Solution

Mahesh earned 167 total points
ID: 39656505
You can offline defragment DAG databases but Its to much time consuming and require complete database re-seeding
Please check below article for offline DAG defragmentation.
LVL 63

Expert Comment

by:Simon Butler (Sembee)
ID: 39656925
That is basically the same thing as I said, just without breaking the DAG. Either way a full reseed is involved.
I haven't done an offline defrag since Exchange 2007 was released. It isn't risk free and requires too much downtime. Just move everything in to new databases.


Author Comment

ID: 39671629
Database size reaches to 700 GB and observed that there is no limit set on mailbox size. some MAC users have more than 20 GB mailbox size.

Can mailbox size effect on performance on mailbox server. what is defualt size of per mailbox.
LVL 37

Accepted Solution

Mahesh earned 167 total points
ID: 39671664
Whatever limit you have set on mailbox database level in organization configuraion\database properties is the actual default size for all mailboxes in that database.
Please check there what size you have set.If nothing is there, it means it is unlimited Quota.

In your case that default limit checkbox is unchecked or set manually on mailboxes to some higher value causing default database size limit is overwritten.

Run below cmdlet on exchange server to find out how many users are not obeying the database default limit.
get-mailbox -filter { usedatabasequotadefaults -eq $false -AND recipientTypeDetails -eq 'usermailbox'  }
[PS] C:\>Get-MailboxDatabase "Mailbox Database 1" | Get-MailboxStatistics | Sort totalitemsize -desc | Export-CSV C:\mailboxes.csv
This will give you idea...

If you wanted to set limit on database size or default limit on mailboxes, then you must 1st archieve those hugh mailboxes contents and bring them within default size limit

Maximum database size limit in Exchange 2010:

mailbox size effect on performance

Ideally, it depends how your exchange mailbox server is designed


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