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  • Database Growth After Move Mailbox

    Hello,

    I have two Exchange 2003 servers. I'm moving mailboxes from one server to
    the other using move mailbox task. During the process the database grows from
    90GB on the old server to 250Gb on the new server. I suspect this is because
    of links that exist between attachments and recepients and are broken when
    the mailboxes are moved. The same situation happened a year ago when I
    migrated from Exchange 5.5 to 2003. The database grew from 30Gb to 100Gb.
    This situation is very problematic. Does anyone has a solution for this
    problem?

    Thanks.
    Eli Leibzon

  • #2
    Re: Database Growth After Move Mailbox

    1. Please review:

    http://www.petri.com/defragment_exch..._databases.htm

    2. ALso, if you move mailboxes then you might breck the links from duplicate notes to another. In regular server: one user send email to 5 users with 1 files of 1 MB. The database size will be increase in ~1.10-1.20 MB and not 5 MB due the fact the Exchange save only one email copy and link it to 4 peoples.
    After the migration you breck this links and then the server will use 5 MB.

    Regards,

    Yuval
    Best Regards,

    Yuval Sinay

    LinkedIn: https://www.linkedin.com/in/yuval14, Blog: http://blogs.microsoft.co.il/blogs/yuval14

    Comment


    • #3
      Re: Database Growth After Move Mailbox

      Thanks for the reply.
      The cause of the growth is well understood. The question is will the defragmentation of the database will help, shrink and re-establish these broken links which were duplicated. What I mean is: If I had an attachment which I sent to 10 receipients and it was saved once with pointers to it and I moved these 10 mailboxes to other server, the pointers broke and the attachment replicated itself by 9. Will these 9 attachments will be deleted and pointers will be re-established on the new server after offline defrag and eventually the database will go down in size?
      Eli Leibzon

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      • #4
        Re: Database Growth After Move Mailbox

        I have the same issue and my database size grew as well. If I run the offline defrag will the databze size shrink and the pointers will be re-established?

        Comment


        • #5
          Re: Database Growth After Move Mailbox

          You do realise that youre exchange server does an online defragment, usually every night. This will then create some white space which will be used before the database starts to increase again.

          Comment


          • #6
            Re: Database Growth After Move Mailbox

            Yes, I do realise, however I need to shrink the size of the database because the target server is hosting the database on an iSCSI LUN which cannot accomodate a space of 300GB because of disk shortage.
            Is offline defrag will actually shrink the database file or will it create a white space in the database and leave the database file with the same size?
            Eli Leibzon

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            • #7
              Re: Database Growth After Move Mailbox

              The offline defrag will clear space from the drive. There are pitfalls in doing this so please ensure that you have a known good backup.

              ESEUTIL

              Comment


              • #8
                Re: Database Growth After Move Mailbox

                After the mailbox is moved the links are not recreated, even if you perform offline defrag. You would see the database size increase also when you:
                - restore a mailbox from brick level backup (this also breaks the concept of single store)
                - exmerge out & in a mailbox
                - move mailbox to another DB

                Also note that online defrag does not recover disk space. It rearranges the data inside the database file, but does not free the white space in the file to the filesystem. Only offline defrag can reduce db file size.

                For more info: http://www.petri.com/defragment_exch..._databases.htm
                Guy Teverovsky
                "Smith & Wesson - the original point and click interface"

                Comment


                • #9
                  Re: Database Growth After Move Mailbox

                  Now you managed to confuse me! Wullieb1 said that online defrage creates white space while Guy says that it doesn't!!! Does anyone has an official link to a microsoft document on the issue?
                  Last edited by eleibzon; 11th November 2005, 15:03.
                  Eli Leibzon

                  Comment


                  • #10
                    Re: Database Growth After Move Mailbox

                    A few suggestions...

                    Have a look at third party Exchange management software.

                    There are a couple of them that will pull attachements out of the exchange databases and store them in a separate one, creating a single-instance-store 'somewhere-else'.

                    The files can still be accessed by the user from Outlook, as before.

                    I guess you are using Exchange 2003 Enterprise and that would give you the option of using 'more-than-one' mailbox database. These can be distributed on different harddrives and kept a bit smaller (nice in recovery situations..).
                    Note that Exchange doesn't handle single-instance-storage between databases, but some (or all?) third party Exchange Store products do.

                    One more :
                    Get your users to move attachements to 'other storage', like home or public file shares. Then run an offline defrag to shrink the db.


                    //M

                    Comment


                    • #11
                      Re: Database Growth After Move Mailbox

                      Originally posted by eleibzon
                      Now you managed to confuse me! Wullieb1 said that online defrage creates white space while Guy says that it doesn't!!! Does anyone has an official link to a microsoft document on the issue?
                      I never actually said that the white space was recovered by the file system.

                      The white space that is created is the re-used by exchange before increasing the size of the database.

                      From MS

                      There are two types of Exchange database defragmentation: online and offline.

                      Online Defragmentation
                      Online defragmentation is one of several database-related processes that occur during Exchange database maintenance. By default, on servers running Exchange 2000 Server and Exchange Server 2003, Exchange Server database maintenance occurs daily between 01:00 (1:00 A.M.) and 05:00 (5:00 A.M.). Online defragmentation occurs while Exchange Server databases remain online. Therefore, your e-mail users have complete access to mailbox data during the online defragmentation process.

                      The online defragmentation process involves automatically detecting and deleting objects that are no longer being used. This process provides more database space without actually changing the file size of the databases that are being defragmented.

                      Note: To increase the efficiency of defragmentation and backup processes, schedule your maintenance processes and backup operations to run at different times.

                      You can schedule database defragmentation in two ways:

                      To schedule database defragmentation for an individual database, use the Maintenance interval option on the Database tab of a mailbox store or public folder store object.
                      To schedule database defragmentation for a collection of mailbox stores and public folder stores, use the Maintenance interval option on the Database (Policy) tab of a mailbox store or a public folder store policy.
                      For information about how to create a mailbox store policy or public folder policy, see "Create a Mailbox Store Policy" and "Create a Public Folder Store Policy" in Exchange 2000 Server or Exchange Server 2003 Help.

                      Offline Defragmentation
                      Offline defragmentation involves using the Exchange Server Database Utilities (Eseutil.exe). ESEUTIL is an Exchange Server utility that you can use to defragment, repair, and check the integrity of Exchange Server databases. It is available through the following sources:

                      If you are running Exchange 2000 Server, ESEUTIL is located in the E:\Support\Utils folder of your Exchange 2000 CD (where E:\ is the drive letter of your CD-ROM drive).
                      If you are running Exchange Server 2003, ESEUTIL is located in the F:\Program Files\exchsrvr\bin directory after running Exchange Server 2003 Setup (where F:\ is the drive letter of the drive to which you installed Exchange Server).
                      You can only perform offline defragmentation when your Exchange Server databases are offline. Therefore, your e-mail users will not have access to mailbox data during the offline defragmentation processes.

                      During the offline defragmentation process, Eseutil.exe creates a new database, copies the old database records to the new one, and then discards unused pages, resulting in a new compact database file. To reduce the physical file size of the databases, you must perform an offline defragmentation in the following situations:

                      After performing a database repair (using Eseutil /p)
                      After moving a considerable amount of data from an Exchange Server database.
                      When an Exchange Server database is much larger than it should be.

                      Important: You should consider an offline defragmentation only if many users are moved from an Exchange Server database or after a database repair. Performing offline defragmentation when it is not needed could result in decreased performance.
                      When using Eseutil.exe to defragment your Exchange Server databases, consider the following:

                      To rebuild the new defragmented database on an alternate location, run Eseutil.exe in defragmentation mode (using the command Eseutil /d) and include the /p switch. Including the additional /p switch during a defragmentation operation enables you to preserve your original defragmented database (in case you need to revert to this database). Using this switch also significantly reduces the amount of time it takes to defragment a database.
                      Because offline defragmentation alters the database pages completely, you should create new backups of Exchange Server 2003 databases immediately after offline defragmentation. If you use the Backup utility to perform your Exchange Server database backups, create new Normal backups of your Exchange Server databases. If you do not create new Normal backups, previous Incremental or Differential backups do not function because they reference database pages that were re-ordered by the defragmentation process.

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