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  • Operation with RAID-5 setup

    Hi Guys, I have a HP Proliant DL380G5 running on windows server 2003 with 7 x SCSI harddisk with Raid-5 configured (no spare drive). It has 2 logical drives c: and d:

    Recently, one of the hdd in slot2 failed and the whole server was unable to boot into it's OS. (Please refer to the image). I was then told that this happened because no spare harddisk were configured. If there were a spare, the spare would take over the failed hdd in the event. Can anyone here give some advice on this?

    Anyway I wasn't the one who did the initial setup. Now that the setup is as such, can I still change the raid 5 configuration?
    Attached Files

  • #2
    Re: Operation with RAID-5 setup

    If there is a failed disk and no spare, then the array is indeed faulty. Once you add a replacement disk to the array, it should just rebuild by itself.

    You can't recreate the array, or change the array type, without the loss of all data on the drive.

    Does this make sense ?
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    • #3
      Re: Operation with RAID-5 setup

      If the C: drive is an independent disk then it presumably should have a mirror (which has failed??) or it should have been configured as a mirror (RAID 1).

      What is the drive configuration?

      I had a 4 drive server that used a combination of RAID 1 and RAID 5 to create three drives (OS, Pagefile and Data).
      Attached Files
      A recent poll suggests that 6 out of 7 dwarfs are not happy

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      • #4
        Re: Operation with RAID-5 setup

        Originally posted by tehcamel View Post
        If there is a failed disk and no spare, then the array is indeed faulty. Once you add a replacement disk to the array, it should just rebuild by itself.

        You can't recreate the array, or change the array type, without the loss of all data on the drive.

        Does this make sense ?
        Hi, it does make sense to me as I have tried the first step to replace the faulty hdd to a new one and it does rebuild.

        Does it mean that if I am prepared to lose all my data, I can change the array type/configurations?

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        • #5
          Re: Operation with RAID-5 setup

          Originally posted by Blood View Post
          If the C: drive is an independent disk then it presumably should have a mirror (which has failed??) or it should have been configured as a mirror (RAID 1).

          What is the drive configuration?

          I had a 4 drive server that used a combination of RAID 1 and RAID 5 to create three drives (OS, Pagefile and Data).
          I do not have the config with me now but I believe it is only raid-5 configured. Not sure if there is a raid-1 mirror.

          So based on the way you configured your drives, may I know what is the fault tolerance? What is the number of hdd that can fail with your server still operating?

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          • #6
            Re: Operation with RAID-5 setup

            RAID5 can sustain the loss of one single disk, due to the way it writes with a parity block. It will lose functionality, but the array is not destroyed. If you have for instance, a RAID0 set, and a drive fails, you lose everything.

            If you have a hot spare (either a Global hotspare, or one within your diskpool) then it should rebuild automatically. Otherwise, bung a spare in, and it'll rebuild. Ideally, you should do this outside of critical processing time, as it may slow things down.

            It won't sustain the simultaneous loss of two disks, or the subsequent loss of a second disk following a first failure. It also probably won't survive a failure of a second disk during a rebuild.


            With regards changing the array type, yes, if you are happy with the fact that your data will be lost, you can change the array settings.
            It's just like formatting your disk - you'll need to delete the existing array, and create a new array.

            Check out these two articles for some more information
            http://en.wikipedia.org/wiki/RAID
            http://en.wikipedia.org/wiki/RAID_5#RAID_5
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            • #7
              Re: Operation with RAID-5 setup

              Originally posted by tehcamel View Post
              RAID5 can sustain the loss of one single disk, due to the way it writes with a parity block. It will lose functionality, but the array is not destroyed. If you have for instance, a RAID0 set, and a drive fails, you lose everything.

              If you have a hot spare (either a Global hotspare, or one within your diskpool) then it should rebuild automatically. Otherwise, bung a spare in, and it'll rebuild. Ideally, you should do this outside of critical processing time, as it may slow things down.

              It won't sustain the simultaneous loss of two disks, or the subsequent loss of a second disk following a first failure. It also probably won't survive a failure of a second disk during a rebuild.


              With regards changing the array type, yes, if you are happy with the fact that your data will be lost, you can change the array settings.
              It's just like formatting your disk - you'll need to delete the existing array, and create a new array.

              Check out these two articles for some more information
              http://en.wikipedia.org/wiki/RAID
              http://en.wikipedia.org/wiki/RAID_5#RAID_5

              Well I see. Thanks for the useful information tehcamel.

              Cheers!

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              • #8
                Re: Operation with RAID-5 setup

                easy as buddy. good luck with changing the type.
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                • #9
                  Re: Operation with RAID-5 setup

                  That is not correct TehCamel.
                  You should have functionallity if one drive fails, however it will be degrated.
                  If every time a server crashes or stop working when just one drives fails....

                  Anyhow, In servers I'd never worked with hotspare since the systeem kept working dough it might be a bit slower...
                  Unless something has been really changed within the last 2 years or so

                  @TS, are we talking about an hardware raid configuration or a software raid configuration?
                  Marcel
                  Technical Consultant
                  Netherlands
                  http://www.phetios.com
                  http://blog.nessus.nl

                  MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
                  "No matter how secure, there is always the human factor."

                  "Enjoy life today, tomorrow may never come."
                  "If you're going through hell, keep going. ~Winston Churchill"

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                  • #10
                    Re: Operation with RAID-5 setup

                    you are correct Marcel, thanks

                    I mistyped what I meant I think.. I still have Holiday brain i think
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                    • #11
                      Re: Operation with RAID-5 setup

                      No problem
                      Marcel
                      Technical Consultant
                      Netherlands
                      http://www.phetios.com
                      http://blog.nessus.nl

                      MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
                      "No matter how secure, there is always the human factor."

                      "Enjoy life today, tomorrow may never come."
                      "If you're going through hell, keep going. ~Winston Churchill"

                      Comment


                      • #12
                        Re: Operation with RAID-5 setup

                        The setup you see there is not optimal. I have have had two failures - each time one disk failed and no-one noticed any difference. However, this is a very small network with 30 clients. It is not a good idea to have two types of RAID operating on one disk as apparently it affects performance.

                        The new data server I recently installed to replace that one has 4 1TB disks in RAID 5 for the data and 2 250GB disks in RAID 1 for the OS.
                        A recent poll suggests that 6 out of 7 dwarfs are not happy

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