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How Exchange 2010 deals with whitespace

With Exchange 2007 and older versions, one of the key elements that an Exchange administrator needed to keep an eye on, and caused confusion for newcomers to Exchange was the amount of white space in the database.
This is reported as free space in the event viewer via event ID 1221 during the night and is the result of content being removed from the database by the online maintenance process.

Refer this article for more information:

With Exchange 2010, the behavior of the database has changed.
Instead of performing an online maintenance during a fixed time window, it now does it constantly. This means that content that has passed the deleted item retention period, is removed from the database shortly afterwards, rather than waiting for the next online defrag window.

However because the process is running constantly, event ID 1221 isn’t written to the event log. Therefore an administrator may not have a clue as to how much of the database is white space, and how much is actual content.

This question can be easily answered, using EMS, as the amount of free space in the database is available via get-mailboxdatabase -Status:

Get-MailboxDatabase -Status | Select Servername, Name, AvailableNewMailboxSpace

This command will show you the name of the Server the database is mounted on, the name of the database (which is unique across the Exchange org with Exchange 2010) and the amount of space available in the database for new content.

The result will be something along the lines of this:

ServerName         Name Available            NewMailboxSpace
————–            ——————–            ————————
EXCH10       Mailbox Database        27.75 MB (29,097,984 bytes)

The command used -get-mailboxdatabase -status can provide quite a bit of information about the databases in your Exchange org, use the |fl command to see the full list.

Always remember that when you perform stress testing/sizing for your Exchange 2010 environment, the IOPS created by this online maintenance should be kept in mind. Jetstress is a tool to play with.

Team @ MSExchangeGuru

12 Responses to “How Exchange 2010 deals with whitespace”

  1. Champ Says:

    Thank you

  2. Anand Sunka Says:

    Hi Guru’s,

    To use the Available White Space, do I need to do the Offline defragment.

    Any help really appreciated

    Anand S

  3. Kishore Says:

    Is there a way in Exchange 2010 to schedule the online defragmentation not just leaving the option to the server ?

  4. Carl M Says:

    Cheers for the info!

  5. Shyam Says:

    Is their is a way in Exchange 2010 to find out the Information in event viewer about a online maintenance.

    such as in exchange 2k3, we use to get 700 series of event ids generated.

  6. World Email Database Sale Says:

    I’m extremely impressed with your writing talents and also with the format in your blog. Is that this a paid subject matter or did you modify it your self? Anyway keep up the nice quality writing, it is rare to look a nice blog like this one these days..

  7. justin Says:


  8. Prabhat Says:

    “Sorry for late reply”. You might have already got the answers but I will still prefer to answer you in case you have not heard.

    Anand Sunka: Yes, you need to go for offline defrag but I would prefer moving mailbox to new DB which will reduce production outage.

    Shyam: This cmd “Get-MailboxDatabase -Status | Select Servername, Name, AvailableNewMailboxSpace” is very quick why do you need to find in events.

    World Email Database Sale: Thank you.

    Thank you for reading our blog. Keep visiting us.

  9. zax Says:

    Brilliant, thanks

  10. KennyV Says:

    What is whitespace is not filled up. i have almost 60GB White space, but still the edb size is growing. Is whitespace only filled with newly created mailbox or is it also used for existing mailboxes which are growing?

  11. Gowtham Says:

    Hello Guru,

    Am reailly impressed the way about articles.

    i had a doubt that
    1.How can we perform the online Fragmentation in 2010?
    2.Is the Fragmention is done by the server itself, if that is the case no point of doing the Offline Fragmentation if, am right?

  12. Ahmed blaze Says:

    Shyam: The defragmentation event id would be 700 and the 701 will be generated upon completion of the online defragmentation.

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