Link to home
ROBERTO PAREJAFlag for United States of America

asked on

Running eseutil on 1 database.

Hi Team,

I have 3 email domains (i.e., and installed on an Exchange 2016 Server. One of those ( have a lot of White Space that I can release and recover some disk space.


1) If I dismount that domain database specifically (, then run the eseutil.exe to defragment it, will the other 2 email domains ( and keep working without any problems while this maintenance is being run?

2) The database is on the D: drive. I have lots of space on the D: drive but not that much on the C: drive (where the system temp is used). Will the eseutil.exe utility use a temporary  area to work with, and leave the same original database, or that temporary area will become the NEW database?



Avatar of Amit
Flag of India image

Just create new db and move mailbox to new db and get rid of old db. This way you get space without downtime


Thanks Amit,

I think the following process would be a lot easier to give it to a tech here.
And we really don't mind the downtime because that specific ccc database has already been migrated to the cloud, but management does not want to delete it from our on-prem server, I just want to optimize the space.


Dismount-Database ccc
eseutil.exe /d "d:\exchange databases\ccc\ccc.edb" /t "d:\exchange databases\temporary"
Mount-Database ccc


1) If I do it this way, will the email domains aaa and bbb keep working without problems?
2) Will the eseutil copy the temporary database back to the original location and rename it as ccc?


My simple advise just leave db as it is, you shouldn't be worry about whitespace in exchange db. Exchange will use it


White space is the database storage area that has become available for storing new data because of the deletion of existing data. Exchange, instead of reducing the database size, makes this space available for the addition of new mailboxes. This reclaimed storage area is known as White space. Also, it is known by names such as available mailbox space, free space, and free database pages.

Rest it is on you to decide. I am giving you the best advise.

The thing is that I am running out of space on drive D: for databases aaa and bbb.

I would expect to release about 400GB of whitespace from ccc according to the following result:
[PS] C:\Windows\system32>Get-MailboxDatabase ccc -Status | Format-List Name, DatabaseSize, AvailableNewMailboxSpace

Name                     : CCC
DatabaseSize             : 465.6 GB (499,961,036,800 bytes)
AvailableNewMailboxSpace : 459 GB (492,802,572,288 bytes)

I think this extremely high space (459GB) shown on AvailableNewMailboxSpace is because about 180 email accounts have been deleted and completely removed from the ccc database.

Now there are only 3 users left on the ccc database and I am 100% sure that the ccc database will not grow at all.

havent used eseutil for quite a while but you will need about double the size of the new dbas freespace, as it effectively copies data to the new 'tempdb' , then deletes the initial and renames tempdb.  

but it also writes all this data to the log file as well, so that needs space as well.

the defrag does have advantages over the copy to new, as it maintains any system folders for that EXS instance.

You need 1.5 times of disk space to perform offline defrag. Creating new db and moving 3 users to new db won't take much space. Check the best possible option you want to choose
Thanks for your input.

It makes complete sense moving the 3 users to a new DB.
1) Is the process the same for the distribution groups and contacts?
2) After moving everything to NEW-CCC database, I just unmount the old CCC database and delete it?

Thanks again!
Avatar of Amit
Flag of India image

Blurred text
View this solution by signing up for a free trial.
Members can start a 7-Day free trial and enjoy unlimited access to the platform.
See Pricing Options
Start Free Trial