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So torn on Offline Defrag......Is there a final word? To do or not to do?

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  • So torn on Offline Defrag......Is there a final word? To do or not to do?

    I am so torn on offline defrag. I realize it has its pitfalls and am somewhat scared to do it, but I could use the free space it would clear up for us. Is it better to just purchase a third party utility to do the job, use eseutil /d or just not do it at all?

    I am planning on moving my DBs over to our new iSCSI SAN and would like to do some maintainence on our DBs 1st. I'd mainly like to shrink the size as much as possible to help streamline the move to the iSCSI LUNs.

  • #2
    Re: So torn on Offline Defrag......Is there a final word? To do or not to do?

    I would vote against running it, expecially if your dbs are large. If you are looking to move the db's to a new SAN you might consider creating empty db's on the SAN and moving mailboxes over. You'll lose your whitespace and have fresh db's.

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    • #3
      Re: So torn on Offline Defrag......Is there a final word? To do or not to do?

      Just had to do this over the weekend.
      Our Exchange 2003 DB was at 77GB so the store kept unmounting and as i didn't have 110% of disk space spare, i had to:
      • unmount the store on friday
      • copy the DB's over the network to our storageserver
      • made another copy of the DB's (just in case the defrag screwed it up)
      • defragged the 'copied over' DB's with eseutil
      • copied the defragged DB's back onto the exchange server
      • reboot exchange server
      • Gleaned back about 6Gb in total
      Whilst not the best method, and it took a good day to do (hence the weekend when no users were connected).

      I'm sure there are better ways though.

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      • #4
        Re: So torn on Offline Defrag......Is there a final word? To do or not to do?

        Originally posted by Greg.Allen View Post
        I am so torn on offline defrag. I realize it has its pitfalls and am somewhat scared to do it, but I could use the free space it would clear up for us. Is it better to just purchase a third party utility to do the job, use eseutil /d or just not do it at all?

        I am planning on moving my DBs over to our new iSCSI SAN and would like to do some maintainence on our DBs 1st. I'd mainly like to shrink the size as much as possible to help streamline the move to the iSCSI LUNs.
        Thats entirely dependant on "how" much recoverable space is available. In the eventvwr on the Exchange create a filter for eventID 1221 in the Application log. It will tell you how much space is available there. Additionally if the databases are very large then that means downtime as well as you having to find the equivalent amount of space for Exchange to defrag the store and create a new one. Also if you are using the enterprise edition of Exchange and you're worried about you're Exchange hygiene just create a new store and migrate the mailbox's into that. As a rule offline defrags are a waste of time.

        If you're interested in an application that can do a defrag on the exchange store have a look at Perfect disk. To be fair though it only leverages Esutil which is already present in the Bin folder on the Exchange Server.

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        • #5
          Re: So torn on Offline Defrag......Is there a final word? To do or not to do?

          The key things are how much space you are going to gain, whether you can justify the downtime and whether you are on Enterprise edition.

          I wouldn't even consider an offline defrag unless I am going to gain at least 50% of the free space. However since the release of Exchange 2003 SP2, I haven't done a single offline defrag. They are unnecessary and a waste of time.

          Simon.
          --
          Simon Butler
          Exchange MVP

          Blog: http://blog.sembee.co.uk/
          More Exchange Content: http://exchange.sembee.info/
          Exchange Resources List: http://exbpa.com/
          In the UK? Hire me: http://www.sembee.co.uk/

          Sembee is a registered trademark, used here with permission.

          Comment


          • #6
            Re: So torn on Offline Defrag......Is there a final word? To do or not to do?

            I know it sure seemed like a lot of effort to regain 6Gb of space to me, but am interested in why the offline defrag is a waste of time.

            I would prefer the new DB and move mailboxes to it, but that only works if you have the space. (and if you have the space, then maybe all the effort even doing that might not be worth it).

            In exchange 2007, is there anything new wrt to defrags? (online/offline) Seems like maybe something could be run in the background freeing up the free space.

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            • #7
              Re: So torn on Offline Defrag......Is there a final word? To do or not to do?

              For 6gb I wouldn't even be considering it. I wouldn't be able to justify the downtime for such a tiny gain.

              Nothing has changed in Exchange 2007, except all versions support multiple databases. Therefore instead of doing an offline defrag, you just create a new database, move all the data across and drop the original. Zero downtime, zero risk.

              Simon.
              --
              Simon Butler
              Exchange MVP

              Blog: http://blog.sembee.co.uk/
              More Exchange Content: http://exchange.sembee.info/
              Exchange Resources List: http://exbpa.com/
              In the UK? Hire me: http://www.sembee.co.uk/

              Sembee is a registered trademark, used here with permission.

              Comment

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