Hi I wonder if anyone can help.

We have a situation whereby over night we have ran out of disk space on a partition.  We have DAG environment and have 3 mbx servers and 3 CAS servers.

By calculations we have 119 Mailboxes mounted on this partition and if all had reached the 4gb we allow the mailboxes to grow to (which they aren't) this would account for 476 GB in size?  Looking at the .edb it's current size is 560GB.  Looking at forums people seem to mention that Exchange doesn't clear up after itself particulary well and often leaves a lot of white space in the database?  Is this the case and if so does anyone have any solutions to remove it?

Many Thanks

Hello

you can check white space: Get-MailboxDatabase -Status | Select-Object Server,Name,AvailableNewMailboxSpace
and check dumpster size: Get-MailboxStatistics database <DataBase> | Sort-Object TotalItemSize -Descending | ft DisplayName,@{label="TotalItemSize(MB)";expression={$_.TotalItemSize.Value.ToMB()}},@{label="TotalDeletedItemSize(MB)";expression={$_.totaldeleteditemsize.Value.ToMB()}},ItemCount

if white space is big you can do:
1 offline defrag -->need maintenance windows because need dismount database
2 if have enough disk create a new database and move mailbox  

Hi,

Exchange will always run online defragmentation on nightly basis, it rearrange the data (database pages really) within the database to have more contiguous white space.
We can run below command to check the maintenance schedule: Get-MailboxDatabse | FL Identity,MaintenanceSchedule
More details about Do we need to file-level defragment Exchange database drives?. For your reference:
http://blogs.technet.com/b/exchange/archive/2004/10/25/247342.aspx

For your question, we can run command as Gador mentioned to get more details about Exchange environment. Especially, mailbox database copy.
More details about Database and Log Performance Factors, please refer to:
https://technet.microsoft.com/en-us/library/ee832791(v=exchg.141).aspx

Thanks