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  • Adding disks to a RAID-5 Environment

    Hello,
    I need to add a disk to an existing RAID-5 Environment for more capacity. The array is controlled by an IBM ServRAID 5i Controller. The server is an IBM xSeries 345, and the O\S is Windows 2003 Standard.

    My question is what do I need to do besides inserting the HDD into the server? The data on the array is mission critical. I hate to guess at installing this drive and risk loosing the data. Any help you can provide is greatly appreciated!!

    Have a great day!
    Thanks in advance for your help.

  • #2
    Re: Adding disks to a RAID-5 Environment

    You need to back up your data, ad the new hard disks, break the old RAID, recreate the new RAID with the new hard disks configured.

    As you said the data is crutial, and can not be risked.

    Best regards,
    Mostafa
    Best regards,
    Mostafa Itani

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

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    • #3
      Re: Adding disks to a RAID-5 Environment

      Originally posted by sanvour View Post
      You need to back up your data, ad the new hard disks, break the old RAID, recreate the new RAID with the new hard disks configured.

      As you said the data is crutial, and can not be risked.

      Best regards,
      Mostafa
      Why would you need to break the array???

      I recently added disks to a Dell server and it added them to the array without any data loss.

      I can't see any reason why you would need to lose any data.

      Comment


      • #4
        Re: Adding disks to a RAID-5 Environment

        Originally posted by wullieb1 View Post
        Why would you need to break the array???

        I recently added disks to a Dell server and it added them to the array without any data loss.

        I can't see any reason why you would need to lose any data.
        Dear Wullieb1,

        It happened to me once I lost the data, while modifying the array, and I did not have any back up. I started after that, backing up everything and then recreating the array.

        Best regards,
        Mostafa
        Best regards,
        Mostafa Itani

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

        Comment


        • #5
          Re: Adding disks to a RAID-5 Environment

          It seems very unusual that IBM would not allow you to add to an array - I know Dell does.

          I took a quick look at the ServeRaid 5.1 User's Guide and it certainly has a provision for editing an exisiting array.

          Read all about it here:

          ftp://ftp.software.ibm.com/pc/pccbbs...df/33p2636.pdf
          Network Engineers do IT under the desk

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          • #6
            Re: Adding disks to a RAID-5 Environment

            Well then, see if your RAID card / driver / application software allows you to add a drive on-line.

            I, for one, would always recommend a backup before proceeding and would lock out user updates during the exercise.
            Cheers,

            Rick

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

            2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

            Comment


            • #7
              Re: Adding disks to a RAID-5 Environment

              I did not think the gist of the thread had anything to do with adding a drive on-line so why would you introduce that now?.

              The questionable practise was breaking the array which I suggest is unnecessary with ServeRaid 4l controllers and Dell PERC 3 and 4 series when adding drives to an array. I just can't see a ServeRaid 5i being any different.

              Secondly, I would think that any IT professional would be backing up anything of importance in the first place and have a disaster recovery in plan. More importantly, as part of your backup plan, you would be doing routine, random restores to see if your back is working properly.

              So if I was going to add a drive to an array, I would make sure my backup was current because we already make the assumtion that the data is important so it must be getting backed up every night. Then I would test my backup by doing random restores to an alternate location.

              Myself, I would add the drive after hours. I prefer to work with the built-in controller software so we are talking about bringing the server down and rebooting it.

              I am not certain what you refer to as 'user updates' but the only person that applies updates to servers I look after is me. If you are referring to auto updates, that's an open invitation for disaster.
              Network Engineers do IT under the desk

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              • #8
                Re: Adding disks to a RAID-5 Environment

                Originally posted by rvalstar View Post
                I, for one, would always recommend a backup before proceeding and would lock out user updates during the exercise.
                I think Rick is refering to User's who update (save) their files to the server.
                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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                • #9
                  Re: Adding disks to a RAID-5 Environment

                  RobW:

                  Yes I was referring to "users" (vs. Microsoft) and thus I thought I implied "after hours". And no, I don't assume folks back up anything as I'm old and have seen the converse too many times.

                  Regarding the introduction of adding a drive on-line, I just looked at the original poster's message:

                  Hello,
                  I need to add a disk to an existing RAID-5 Environment for more capacity.
                  I don't really know what "as-is" and "new" configurations the poster has / imagines but it appears to me as if the poster wishes to add a drive to an existing array.

                  My apologies if I read this incorrectly. Just thought a little "getty up" was what this thread needed.
                  Cheers,

                  Rick

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

                  2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

                  Comment


                  • #10
                    Re: Adding disks to a RAID-5 Environment

                    someone please correct me if I'm wrong, but from my experience you cannot simply add disks to an existing array without compromising the data. You can add hot spares without degrading the array; but increasing storage space is done by recreating the array with the new disk, then having to initialize it. This means that you'll also have to format the array so that windows can use the new logical drive.

                    Since RAID5 stripes the array with parity bits for redundancy, adding a drive to an existing array would throw that parity bit off hence why this is not possible and the array needs to be recreated.

                    I would first make sure you have a good up-to-date, working backup. Then transfer the data to a temporary location, recreate the array with the new disks, get it all setup in windows, transfer the data back to the newly created RAID array. Setup the shares the same way it was setup before.

                    Comment


                    • #11
                      Re: Adding disks to a RAID-5 Environment

                      I'm with you 100%. We need mingle1966 to confirm this was the intent -- to add a drive to an existing array.

                      Kick the users off, back it up, add the drive thus wiping out the old array, restore it, and get on w/ life.

                      Somewhere this thread morphed into adding an array vs. adding a disk to an existing one.
                      Cheers,

                      Rick

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

                      2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

                      Comment


                      • #12
                        Re: Adding disks to a RAID-5 Environment

                        The ability to add a physical disk to an existing array is a function of the RAID controller and some support it and some don't. I can not give you the mechanics on how the parity is handled during the transition, or how the array is regenerated, That topic would best be left for an engineer.

                        I have a ServeRaid 4L controller in one server in my office that supports RAID expansion. I had another server with a Dell PERC 4/D which also supports RAID expansion. Presently I have a Dell 2650 with a PERC 3 controller and I am told it will not support RAID expansion, but I can create a logical disk with the extra hard drive and combine that with a RAID array to make a logical volume. I looked at the user manual from the ServeRaid 5i and it appears you can add to an existing array so where is the debate?

                        I was just reading the specs on the HP Smart Array 5i controller and this supports RAID expansion too.

                        In my opinion, doing *ANYTHING* to a server comprimises the data. What I don't understand is why every always says "make sure you have a good backup". Isn't that a given? What you want to do is make sure your backup works.

                        Try to see the humour in this: I think you would have to be an idiot to look after a server and not back it up (unless it's yours), or replace (or add) a drive and not have a working backup first.
                        Network Engineers do IT under the desk

                        Comment


                        • #13
                          Re: Adding disks to a RAID-5 Environment

                          Originally posted by rvalstar View Post
                          I'm with you 100%. We need mingle1966 to confirm this was the intent -- to add a drive to an existing array.

                          Kick the users off, back it up, add the drive thus wiping out the old array, restore it, and get on w/ life.

                          Somewhere this thread morphed into adding an array vs. adding a disk to an existing one.
                          It seemed pretty clear to me I need to add a disk to an existing RAID-5 Environment for more capacity
                          Network Engineers do IT under the desk

                          Comment


                          • #14
                            Re: Adding disks to a RAID-5 Environment

                            I know it seems silly to keep insisting on the "good backup" bit. Let me tell you a sorry story of mine from way back when I took over a large VAX installation.

                            Had a top notch sys admin that had a thorough full / incremental / differential backup scenario in place. I deleted a key source code file my first week out (oops). Come to find that one of the options he had set on the Files-11 side was omitting the directory structure from the tapes so easy recovery was not possible. I spend the next 12 hours typing in the code from a printout I had fortunately made.

                            My point is, a "good" backup is key. A backup scenario isn't "good" till you've exercised it (recovered files). He had never tried a recovery.

                            Even w/ all the wizardry we have today, do not underestimate Murphy as he will find your weak spot. So it's not just that you take backups (which seems self-evident though I too have seen folks start upgrade endeavors like this while omitting this step) but that you have confidence you can recover if need be.

                            Whether or not the RAID controller in question can add a drive and rebuild without loss of data, the original poster should be prepared for the worst and schedule enough down time for a complete rebuild.

                            I'm going to dismount from my dead horse now, I've beat it enough.
                            Cheers,

                            Rick

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

                            2006-2099 R Valstar. This post is offered "as is" for discussion purposes only with no express or implied warranty of any kind including, but not limited to, correctness or fitness for use. Nothing herein shall be construed as advice. Attempting any activity based on information in this post is done at your own risk.

                            Comment


                            • #15
                              Re: Adding disks to a RAID-5 Environment

                              Originally posted by rvalstar View Post
                              My point is, a "good" backup is key. A backup scenario isn't "good" till you've exercised it (recovered files). He had never tried a recovery.
                              This is the same point I was making.

                              I like your horror story too. We could have a forum dedicated to all these horrors.

                              I took over a company's support last July. Their mail server went down last Friday night and I am 3 hours away. I discovered the hard way there was no backup SMTP server in place.

                              An orthpaedic surgeon working out of our local hospital had the hospital's IT department backing up all his schedules to CD-RW each night using NTbackup. When their computer crashed last year, NTbackup could not read the data on the CD-RW.
                              Network Engineers do IT under the desk

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