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  • Mirror and Raid5

    Hi,

    i'm about to install EX2k3 on Win2K3R2. the server have the following Array setup
    72GB mirror for System(page file include)
    250GB Raid5 for DB
    my question is: should i put the EX2K3 Logs in the mirror or in the Raid5?
    Thx.

  • #2
    Re: Mirror and Raid5

    If this is all you have it would be better to put them on the Mirrored array. The recommended location is to put them on a separate array (mirrored) for the best performance. Here is our config:

    RAID1 = OS, Exchange binaries, Pagefile
    RAID1 = SMTP Queue, TEMP Directory, TMP Directory
    RAID1 = Log Files
    RAID10 = DB Files

    Comment


    • #3
      Re: Mirror and Raid5

      The key thing is to separate the logs and database.

      Therefore what I do when presented with a two array system is partition the first array in to two. Usually 40gb and then the rest.
      The OS and all applications are installed on to the C drive. This includes Exchange.
      On the D drive (partition two of the mirror) I create two directories - Message Tracking Logs and Exchange Transaction Logs.
      I then use ESM to change the location of those two log types to the new directories.

      On the E drive (the RAID 5 in your configuration) a new directory is created for the databases and those are moved there using ESM.

      The idea behind putting the T logs in a separate partition is to protect against something going wrong with Exchange (an email loop for example) and the transaction logs building rapid. The log build up will hit a buffer of a full partition, but Windows will continue to run. A Windows machine with a full boot disk is not a pretty sight.

      The configuration posted above is probably what most people would call a dream scenario and is only something I could justify with a very large number of users or transactions - a couple of thousand. I have run 500 on a two array system with no problems.

      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


      • #4
        Re: Mirror and Raid5

        ok.
        so if i go to put the LOG in the mirror array, and create 2 partitions from this array C: for system and exchange binaries, D: for the LOG, my mirror array is 72GB total. how much for C: and D: drives should i allocate?
        Thx.

        Comment


        • #5
          Re: Mirror and Raid5

          As I wrote above... I usually do OS 40gb and then whatever is left is used for the second partition - so if the array is 72gb then it will be around 30gb.

          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: Mirror and Raid5

            Also, the primary purpose for separating the logs from the databases is that the log files are read from and written to sequentially while the databases are read from and written to randomly. You should never put sequential and random disk I/O on the same physical array unless you have a very small implementation as this will normally cause performance problems. The secondary reason to separate them is for recovery purposes. If you lose your database drive but still have your log file drive you can then restore your databases from a backup and Exchange will roll the transactions forward into the databases so you have a "no loss" restore. You'll get everything back to the point of the loss (in theory).

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            • #7
              Re: Mirror and Raid5

              should 30GB is enough for the LOG?
              as i know the LOG files deleted when you do full exchange backup.
              am i right?

              Comment


              • #8
                Re: Mirror and Raid5

                Yes - The logs are deleted when ever you run full backup:
                http://support.microsoft.com/kb/240145
                CNE 5, CCA, MCSE NT4.0-2003, MCSE 2003 messaging, Exchange Server MVP.
                Tzahi Kolber - IT Supervisor
                Polycom Israel.

                Comment


                • #9
                  Re: Mirror and Raid5

                  Whether it is enough is debatable. That depends on how much you generate a day. For a small site it should be fine. I like to have enough space for a full weekend's log, plus a missed day at either end. That allows for four day weekends or missed backups.

                  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


                  • #10
                    Re: Mirror and Raid5

                    Originally posted by Sembee View Post
                    As I wrote above... I usually do OS 40gb and then whatever is left is used for the second partition - so if the array is 72gb then it will be around 30gb.

                    Simon.
                    Avipenina, my apologies to take this a bit but Simon, why 40GB for the O/S? I have used 25GB in the past on an DC and found it to be more than sufficient. What is your reasoning behing 40GB and does it relate only to Exchange Servers or all servers, DCs & Member? (Educational question for me, not critical of you).
                    1 1 was a racehorse.
                    2 2 was 1 2.
                    1 1 1 1 race 1 day,
                    2 2 1 1 2

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                    • #11
                      Re: Mirror and Raid5

                      I have always built with 40gb. It provides enough room to install what is required. Particularly the case with SBS, as you can't always move things until the wizards have finished their thing.

                      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


                      • #12
                        Re: Mirror and Raid5

                        Thanks.
                        1 1 was a racehorse.
                        2 2 was 1 2.
                        1 1 1 1 race 1 day,
                        2 2 1 1 2

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