3 Replies Latest reply: May 4, 2013 6:36 AM by user8610659 RSS

    raw disk doubt

    user8610659
      Hi,

      I am creating asm diskgroup in hp-ux oracle 10gr2.

      The storage vendor has given me two disks */dev/disk/disk13* and */dev/rdisk/disk13* (they are in raid-5).

      We generally use rdisk i.e, */dev/rdisk/disk13*. I am unable to directly communicate with storage vendor.

      Can any one tell me what is the relation between */dev/disk/disk13* and */dev/rdisk/disk13*?

      *1.Are they raid copy of each other?*
      *2.Are they from same physical disk?*


      Regards,
      Saikat
        • 1. Re: raw disk doubt
          FreddieEssex
          They wouldn't be two disks...it would be the one disk.

          They are not a copy of each other...they are the same physical device/LUN.

          You would utilise the raw device (ie rdisk) for ASM.

          If you were to format the disk for filesystems you would be using the /dev/disk device.
          • 2. Re: raw disk doubt
            onedbguru
            It is my opinion that it is absolutely essential that if you are going use ASM or RAC, that the DBA ***MUST*** learn system, network and SAN administration duties so that you actually understand how your system is configured.

            You were actually only given ONE disk (disk13), You will want to make sure that you partition off the first cylinder and use a partition that contains cylinders 2-last. If you do not understand this terminology, please have your sys admin assist. You would then actually use /dev/rdisk/disk13p1 (or whatever partition number they gave you). Make sure that ALL disks are EXACTLY the same size and NEVER have the SAN "extend/expand" the device. Since the SAN is using RAID5, you can use EXTERNAL REDUNDANCY.
            • 3. Re: raw disk doubt
              user8610659
              Hi,

              Thank you very much for you reply.

              So, here same disk is being shown in two disfferent directories for different purposes.


              Can you give me some link for good study material where I can learn "system administration for DBAs"


              Regards,
              Saikat