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  • how to reclaim space after clearing inboxes

    so on my mail server, i have the inboxes on a 100gig drive. people were letting their inboxes get too big, so i took the liberty of deleting the trash cans and the sent items...

    so i have been to quite a few stations, and have cleared about 10 gigs of messages from users inboxes, but i fail to see a change in the size of the mail store. before, i had 56 gigs used... after, i still have 56 gigs used.

    what do i have to do to see the change reflected in the amount of free space on the drive containing the mail stores?

    will an off-line defragmentation reduce the size of the mail store? or will the mail store always remain the largest its ever been?

    thanks guys.
    its easier to beg forgiveness than ask permission.
    Give karma where karma is due...

  • #2
    Re: how to reclaim space after clearing inboxes

    You will have to do an offline defrag to reduce the size of the physical file(s). Emptying folders and/or doing an online defrag does not reduce the size of the physical file(s).

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    • #3
      Re: how to reclaim space after clearing inboxes

      The physical size of the store never reduces. All that happens is the space that content used is marked as "white space". This white space is used by Exchange first, before expanding the physical size of the store.

      As already pointed out, the only way to reclaim that space is an offline defrag, once the deleted item retention period has expired. Look in the event viewer for event ID 1221 to see how much white space there is.

      Also note that to do an offline defrag the server has to be down continuously. You need at least 110% of the size of the store NOW in free continuous space (so if the store is 100gb then you will need at least 110gb in space). Preferably you need double that, so that you can take a copy of the files for backup.

      Also be aware of the time it takes. The tool processes the files at between and 1 and 4gb per hour, so if your store is 56gb then you could be looking at two days downtime. That it is continuous, as the process cannot be stopped once started. If you stopped it then you would have to restore the backups.

      A 56gb store is not very big for Exchange, personally I wouldn't even consider an offline defrag on that size - certainly not for a 10gb gain.

      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.

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      • #4
        Re: how to reclaim space after clearing inboxes

        Originally posted by Sembee View Post

        A 56gb store is not very big for Exchange, personally I wouldn't even consider an offline defrag on that size - certainly not for a 10gb gain.

        Simon.
        this is kinda what i wanted to hear. in all, i expect there to be a great deal more than 10 gigs free... much more like 30 gigs, but i have been very apprehensive about this procedure. as i said, my mail store is already ~55/56 gigs, but the drive it sits on is only 100 gigs... i lack the required space needed to do an offline defrag without having to point it to another LUN on the Exchange box.


        what size would you consider big? just for discussion sake? i always wondered how big the mailstore can get...

        i was kinda hoping that i would see an increase of performance as i just added a link to the Outlook clients that is a page hosted via the exchange backend... it houses the GFI archive for emails prior to 30 days. there hasn't been a negative impact on perf now, but i was just looking ahead.

        and after reading you guys (and other forums) average for processing time, im afraid i would take down the email for upwards of 40 hours, which is not happening.

        thanks again for the advice sembee and joeqwerty.
        Last edited by James Haynes; 12th February 2008, 15:27.
        its easier to beg forgiveness than ask permission.
        Give karma where karma is due...

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        • #5
          Re: how to reclaim space after clearing inboxes

          A few points:

          1. 10GB is a big amount to reclaim when you consider the database is around 50-60GB. I would do an offline defrag if it were me. (I would do an offline defrag to reclaim even 5GB).

          2. Even though most documentation claims a defrag rate of 1-4GB per hour, I have defragged a 90GB database in 12 hours. I think you'll find that a few hours at most is what's needed. Plan the outage for a weekend and get the approval of management and the end user community.

          3. 100GB is the maximum recommended size of the database according to MS. (I hate to admit it but we have 3 databases that are around 125GB).

          Comment


          • #6
            Re: how to reclaim space after clearing inboxes

            thanks for the time frame for your setup, joeqwerty.
            for argumentitive and educational purposes, could you give me an idea of your hardware specs?
            my BE is on a dell blade:
            poweredge 1855 w/4 gigs DDR-1 (533?)
            2 intel xeon dual-core processors
            mail store sits on a LUN consisting of 6 fiber connected SATA2 drives.
            t-logs are located on LUN ... 3 fiber SATA2 drives.
            does your hardware compare (for better or worse) to the above?

            and finally, am I bad admin for not doing offline defrags regularly? my BE has been up for ~2.5 years, and I have never done one... mainly because I have a very high SLA being that I work in a courthouse. I can pull it off on a holiday weekend, but if it runs over 3 days I'm screwed.

            I've also read that moving the store via ESM will compact the dB also. could I just kill two birds and move the store? I was kinda planning on moving it already, so maybe I just move the store and count it finished?

            thanks again guys for the quick replys!

            petri.co.il/forums rock.
            its easier to beg forgiveness than ask permission.
            Give karma where karma is due...

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            • #7
              Re: how to reclaim space after clearing inboxes

              Your hardware looks good except for the SATA drives (IMHO). How fast are the drives, 7200 RPM? They would probably not stand up in my environment.

              My hardware is as follows:

              Dell PE 2950 Server
              4GB RAM
              Two Dual Core Xeon 3.2GHz processors
              1 on board RAID1 with two 146GB 15K SAS drives = OS & Exchange binaries
              1 on board RAID1 with two 146GB 15K SAS drives = SMTP queue, pagefile, temp directories
              1 on board RAID1 with two 146GB 15K SAS drives = Exchange transaction logs
              1 Dell MD3000 DAS configured with four 300GB 15K SAS drives = Exchange databases

              Five databases total for a combined 600GB of mail

              As far as doing an off line defrag, it is not recommended as a regular maintenence task, so you're not bad for not doing it. Normally you would do it if you stand to reclaim a big amount of space (10% or more IMHO) or if instructed to do so by MPSS.

              I'm not sure if moving the files via ESM will compact them but moving the mailboxes to a new store will. Moving the mailboxes would probably take as long as an offline defrag so there's probably no benefit to doing one as opposed to the other.

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              • #8
                Re: how to reclaim space after clearing inboxes

                Very informative thread. Thanks for the knowledge.
                Andrew

                ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

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                • #9
                  Re: how to reclaim space after clearing inboxes

                  Originally posted by joeqwerty View Post
                  Your hardware looks good except for the SATA drives (IMHO). How fast are the drives, 7200 RPM? They would probably not stand up in my environment.
                  ok now.. no need to be knocki n my SAN array. j/k... but in all seriousness, i'll take the pepsi challange with the array. it would be one thing if the drives actually had to spit out more than their peak output. if you carefully calculate the I/O, then you are only allowing about 300 megs per disk, and since this isnt random reading, per 6.5/7.5 ms times 6 disks... roughly 4 gigs per 1 second of non-random, indexed reads on a redundant arbitrary fiber channel. writes are another story. unfortunately i dont know how to really estimate writes on a RAIDed SAN... sorry. i got my feelins hurt (heehee...) and i had to stick up for the trusty Dell rack. my bad...

                  the size of your mailstores makes me feel better. i had no idea that the stores could be that big... i just knew that there was no limit on Enterprise, but i didnt know how big people let the stores get.

                  Originally posted by joeqwerty View Post
                  Moving the mailboxes would probably take as long as an offline defrag so there's probably no benefit to doing one as opposed to the other.
                  but what i was saying is that i have also planned a storage group migration, effectively moving "Storage_Group1" on 100 gig drive W: to "Storage_Group2" on 400 gig drive X:.... so i was gonna move them already, but now i think i can accomplish both chores in the same 3 day weekend.

                  to further complicate the issue, i cant really use the eseutil with the default switches to do the defrag on the drive it currently exists on because of the storage requirements (the 110%), so the move would allow me to:
                  1. migrate the storage group from the smaller drive to the larger drive
                  2. reclaim the drive space from the 'white-space' incorporated into the store prior to the retention policy.
                  3. spare me from having to use ezutil with crazy switches to span the copy to mulitple drives just to complete an offline defragmentation.

                  that makes sense to me, how bout u qwerty or sembee??

                  minus that last speculation, this thread is squash. ive given the karma up so thanks much to the contributers for the quick responses. my questions were adequately answered. i look foward to any other situational comparasions. feel free to add for the sake of discussion.

                  James
                  Last edited by James Haynes; 13th February 2008, 04:03. Reason: cause i felt like it. how u like me now?
                  its easier to beg forgiveness than ask permission.
                  Give karma where karma is due...

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                  • #10
                    Re: how to reclaim space after clearing inboxes

                    Ok, you made my head hurt with all the talk of IOPS, etc. so I'll take your word for it. LOL. I think you're on the right track with your plan. The only other thing I can add is that you can manually move the files and modify their location information via ADSIEdit, which tends to be faster than using ESM to move them. This is a non-standard method but I've done it with no issues. You may want to see if anyone chimes in with contradictory info.

                    As for the size of our mail stores, they are a little beyond the maximum recommended by MS, which is 100GB. At some point I'll have to break them up, but keeping with MS recommendations means I'll need to implement another RAID array for each of the the logs and databases as they should be kept separated per storage group.

                    Good luck with everything.

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                    • #11
                      Re: how to reclaim space after clearing inboxes

                      Not that I want to argue with Joe, but I have never seen a recommendation from Microsoft on store size. It is a question that comes up frequently but there is never anything produced.

                      The only "recommendation" is a best practise size of individual stores of around 50gb. However the reason for that size is that it provides a good place to get a decent SLA.

                      The other thing to remember is that Microsoft do not recommend offline defrags are carried out at all. There is a posting on the msexchangeteam.com blog that states that. While Joe may feel a 10gb gain is a good gain on a store of that size, I would disagree. I wouldn't want the downtime.

                      I would only do an offline defrag if

                      a. I was going to gain at least 50% of the space back.
                      b. that space is not going to be used again.

                      For example after deploying an archiving solution which removes the content and will keep removing it.

                      Saying that, if you go about 75gb store then you are on Enterprise edition. When it comes to Enterprise edition you have a much more effective way of dealing with a store with lots of white space - create a new store. Move all the mailboxes to that store then drop the old one. Zero downtime, zero impact to the users, zero chances of data loss.

                      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.

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                      • #12
                        Re: how to reclaim space after clearing inboxes

                        Here's the article I referenced regarding the DB size. Whether they mean 50 or 100GB I'm not sure (I think it's 100GB). This is an article based on a BPA scan of my server. As with all things MS, a grain of salt is probably wise when considering their info and recommendations.

                        http://technet.microsoft.com/en-us/l.../aa995715.aspx

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                        • #13
                          Re: how to reclaim space after clearing inboxes

                          They are flagging the store over 100gb and making the recommendation as I have already written about 50gb. I guess they had to select a size that should alert an admin. It would have to be over 75gb otherwise you would confuse a lot of standard edition users and also needs to take in to account the store can be physically larger than 75gb as well.

                          Good that they are flagging it - never seen that message myself because I keep the stores below that level.

                          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.

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