3 Replies Latest reply: Dec 6, 2012 5:16 PM by Victor Armbrust RSS

    Question for ASM

    978013
      Hi ! I'm just wondering if what would be the impact in the performance if for example I want to add a new a disk to ASM from the same physical disk or raid set? Like for example, I have a 400gb HDD and then at first I decided to allocate only 200gb to ASM and when the time comes that it will become full I will be needing to add the remaining 200gb. Would it have an impact especially in the performance because of course for oracle it reads it as a new physical disk but the real deal is that the added disk is just from the same raid set? And also one last thing, is it possible to resize the existing disk in the asm? I will appreciate every answer. Thanks in advance. :)
        • 1. Re: Question for ASM
          71617
          hi,

          I assume you were using raw devvice for ASM, you can not re-size the raw device.
          Since you are using same HDD, not much performance change.

          -KC
          • 2. Re: Question for ASM
            LaserSoft
            Hi

            First take Backup of the database. You can do the resize of existing diskgroup provided if you have additional space in Storage. The Steps are

            1. resize existing LUN from storage (If you have additional LUNs or Space)
            2. Allocate new size from OS
            3. In rolling fashion, shutdown ASM instances.
            4. Only when all ASM have been recycled, you should resize the disk

            Command is below :

            1. SQL> select * from v$asm_operation;
            2. SQL> alter diskgroup DG1 resize disk <diskgroup> size <value>m;
            3. SQL> select * from v$asm_operation;
            4. SQL> select group_number G#, disk_number D#, state, redundancy, name, path, total_mb, free_mb, (total_mb - free_mb) used_mb from v$asm_disk order by name;

            Then you can check from 'asmcmd' also

            -bash-3.00$ asmcmd
            ASMCMD> lsdg

            Thanks
            LaserSoft
            • 3. Re: Question for ASM
              Victor Armbrust
              You can do that if you use disk partition (eg: On Linux + ASMLIB), then you can create the ASM Disks for your diskgroups.

              Eg:

              /dev/sda1 = Partition 1 with ASM HEADER
              /dev/sda2 = Partition 2 without ASM (you can add this later)

              I would not recommend that, after all the disk is the same so, why not use it full for ASM?

              Victor