I've moved about 400 Mailboxes from 2 different database volumes in one MBX server to another empty volume in a different MBX server. Before the migration, I had 20% available space in one and 25% available space in other volume. After the migration, I was expecting decrease in space in these volumes but interestingly data increased! Empty volume that data has been migrated to has right amount, however, volumes that data have been migrated from have less than 5%.

I double checked the databases moving FROM and TO have correct paths, any idea what's going on?

Thanks in advance...

The edb file never really shrinks on it's own.  You should see the amount of white space in the database increase, but the size will never decrease.  If there are no more mailboxes in that database you can either run an offline defrag or remove the DB to reclaim the space.

Thanks for the response. I still have mailboxes in that database. I just don't understand why that database gained even though I moved mailboxes from it... Shouldn't it stay the same at least?  

Hi,

Please check whether you have the logs and database on the same volume. It is recommended to setup a new volume for logs.

Additionally, we need to check the Database White Space first. If there is little white space, it is recommended to do the following steps:

1. Create a new database and associated database copies.

2. Move all mailboxes to the new database.

3. Delete the original database and its associated database copies.

Regards,

1. Agree with Winnie in that during mailbox moves you will generate logs for both DB's unless you turn on circular logging however that has its own challenges as well.  Depending on the backup product your using you could schedule more frequent backups during migration to truncate the logs reclaiming space but that also puts more load on the server
2. The other issue to consider is your deleted item and mailbox retention settings.  If the items or mailboxes have not passed the retention period the space will note be released until that time