Exchange 2003 - 'whitespace' - availability for re-use

Posted on 2006-03-31
Last Modified: 2008-03-04
The pr1v1.edb physical size has continuosly grown on our exch 2003 server box - inspite of users being harassed to delete un-neccesary emails, which I know they have been doing.
So, it appears that the space created by message/mailbox deletions has not been re-used.

The Online defrag has not been running on priv1.edb ( although it has on other mailstores) - and suspect this is because the back-up exec exchange agent is doing its backup thing at about the the same time.

So,my question/s are -

a/ would the 'whitespace' created by the mailbox & message deletions not have been available for use by subsequent message storage because the online defrag has not been running ? and

b/ If we do get an online defrag to run will the whitespace  become available for use ?

c/ Assuming the online defrag does not complete on its first night for whatever reason, will the porportional amoutn of space it did defrag be available for use? ( accept that I won't knwo what this is until the defrag does, eventually finish)

d/ How can I ' force' and online defrag ? Have looked but cannot see this option anywhere obvious.


Question by:r0lla
    LVL 27

    Expert Comment

    This may be an interesting article to read:

    Basically if online maintenance never runs then you will never see whitespace because online maintenance cleans up any messages that have passed their deleted item retention date.

    Author Comment

    Thanks, I think. so "you will never see whitespace" means that Exch2k3 will not re-use the space for storage, and will continue to grow the physical size of the db ?
    LVL 27

    Accepted Solution

    Read that article.

    One of the things that happens during online maintenance is that all deleted items are checked against the deleted item retention time. If this has expired then that data is marked as whitespace.
    So if online maintenace has not been running then how will it determine that deleted data has passed the deleted item retention time?

    "and suspect this is because the back-up exec exchange agent is doing its backup thing at about the the same time."
    I suggest that you alter your schedule for the backups and the online maintenance. They should not overlap.

    Are your backups taking a long time to run?
    If so then how big is your database?
    Are you backing up individual mailboxes? This can lead to an extended backup window.
    If so then I suggest that you look into discontinuing backups of individual mailboxes. With Exchange 2003 you can restore an information store backup to a recovery storage group. There is an article on this in the MS Knowledgebase.
    LVL 2

    Expert Comment

    Depending on how many mailboxes you have and size the best way i have found of cleaning a database is to make a new one, and move the mailboxes accross to it then remove old .edb.stm. Of course if there is a retention on deleted items you wont see space available till deleted items have passed retention time. Again this is only useful when you only talking about 50 mailboxes or there abouts. Since they are on the same exchange moves dont take long to do and you are certain all whitespace will be moved.
    LVL 14

    Expert Comment

    In order to reclaim the white space, the storage had to be dismounted and I believe exmerge had to be used.  We ran across that issue about a year ago and faced with the dilemma of freeing space vs up-time; we foregone reclaiming the white space due to the estimated amount of time it would take to do so.  We didn't have any clear benefits with this process as after all of the net deletes and additions of user data, the over all stores kinda stablized to a size (with some additional slow growth).


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