Exchange 2010 - Big discrepancy between database sizes and sum of all mailbox sizes RRS feed

  • Question

  • HI,

    I have Exchange 2010 Sp2 RU7, I have lot of database where the size of the EDB it almost double the sum of the size of the mailbox.

    I calculate the size of the mailbox in 2 two and the where similar, (Mailbox size + Dumpster)  and the sum of all folder size.


    Name USER12
    DatabaseSize (MB) 141.064
    AvailableNewMailboxSpace (MB) 3
    EDB - WhiteSpace 141.061
    Sum of Mailboxes Size + Dumpster 75.206

    I not using Enterprise Vault.

    What I´m I doing wrong? what my I forgetting do add? 

    Antonio Mourao

    Monday, November 4, 2013 12:12 PM

All replies

  • If you have 141MB of free space, doesn't that answer your question?

    Removing messages/mailboxes from the database doesn't shrink the size of the database.

    Create another database and move all your mailboxes there. When there are no longer any mailboxes assigned to the old database, remove it from Exchange and then delete the database and log files for the old database. The new database should be approximately the size of the mailboxes (allowing for indexes, views, etc.).

    --- Rich Matheisen MCSE&I, Exchange MVP

    Monday, November 4, 2013 10:44 PM
  • Hi Rich, sorry for the confusion (I'm Portuguese and use the coma for decimal not the dot) let me repeat the number but in GB

    DatabaseSize 141 GB
    AvailableNewMailboxSpace 3 MB
    Sum of all Mailboxes Size with Dumpster 75 GB

    I have 66 GB of space in the database that I can make to anything.

    I don´t have disconnect mailbox in this database.

    What I did is remove, all mailbox to a new database, let the maintenance plan run as schedule. Then get the mailbox database statistics .

    I'm hoping this post also will help me understating why my Public Folder Database (Only for OAB, FreeBusy, etc.) as 50GB of size, we don´t have any file store in this PF db.

    Thanks for your answer.

    Antonio Mourao

    Monday, November 4, 2013 11:03 PM
  • I move all the mailbox, the new Database is nearly 80Gb in size and the AvailableNewMailboxSpace is 139GB in the old database, what where the 66GB that are not transferred?                                             

    Antonio Mourao

    Tuesday, November 5, 2013 8:48 AM
  • I think that one of your misunderstandings has to do with the actual amount of data in a database. In Exchange 2007 there's still concept of Single Instance Storage, even though it's restricted to attachments. So, for example, if a message with a 1MB attachment is sent to two mailboxes in the same database the attachment is stored only once but each mailbox's size increases by 1MB.

    There's also the internal overhead within the database. Things such as database tables, indexes, free space, etc. In a database that's reached some level of stabilization (assuming that people actually delete messages and those message "age out" of the recoverable items) the overhead is typically about 20% - 30% of the database size.

    If you've had some large mailboxes from which many messages have been removed there's probable a considerable amount of white space in the database.

    There are also "system" mailboxes that exist within the database.

    If you're really interested, you can use ESEUTIL with the /MS option to do a Database Space Tree Dump. http://technet.microsoft.com/en-us/library/aa996139(v=exchg.65).aspx (for an example -- ignore the .STM file stuff).

    --- Rich Matheisen MCSE&I, Exchange MVP

    • Marked as answer by Tonaco Wednesday, November 6, 2013 10:03 AM
    • Unmarked as answer by Tonaco Wednesday, November 6, 2013 10:04 AM
    Tuesday, November 5, 2013 10:40 PM
  • Hi Rich

    I understand all that, my problem is that this database grown lot´s more than I spectated, and overhead of 40 to 50% I almost impossible to maintain. I in conclusion got to go buy more disk. 

    Antonio Mourao

    Wednesday, November 6, 2013 10:03 AM
  • Until you run ESEUTIL /ms on that database you won't know what's occupying the space.

    Running "set-mailboxstatistics -database <db-name>" might reveal something (e.g. a SystemMailbox{*} that's very large), but it won't provide much detail.

    --- Rich Matheisen MCSE&I, Exchange MVP

    Thursday, November 7, 2013 10:42 PM

    Hi Rich,

    My Database after moving user:

    DatabaseSize 131.4 GB
    AvailableNewMailboxSpace 86.81 MB
    User Mailbox 0
    User Disconnected 302
    TotalItemSize 27.873
    itemcount 148.005
    TotalDeletedItemSize 46.332

    After I removed the Disconnected user(SoftDeleted):

    AvailableNewMailboxSpace 130.7 GB

    Here are the Eseutil /MS, after I remove all the mailbox and before I removed all the softdeleted mailbox. (The maintenance schedule has stopped.), I'm still trying to understand this log.


    I remove 74 GB of mailbox (softdeleted) and gain 130 GB of AvailableNewMailboxSpace. 

    Antonio Mourao

    • Edited by Tonaco Monday, November 11, 2013 2:17 PM Edit Hyperlink
    Monday, November 11, 2013 2:15 PM
  • It looks like you have a lot of large attachments ("Long Values" or items that cannot be stores in a single page).

    --- Rich Matheisen MCSE&I, Exchange MVP

    Monday, November 11, 2013 10:57 PM
  • Thanks Rich, where can I learn to understand better this value?

    Antonio Mourao

    Tuesday, November 12, 2013 4:58 PM