5 Replies Latest reply: Mar 19, 2013 6:05 AM by 917699 RSS

    Asm Benefits

    user410867
      Dear All Guru's

      I have question's to clarify me doubt why we need to implement Asm while we get all feature in Raid 10.Why any organization should implement ASM.Can you please elaborate the benefilt of asm and raid level.It's help me alot.

      Regards,
      Merri
        • 1. Re: Asm Benefits
          Eddie Essex
          If you currently have RAID10 then you can specify external redundancy when creating disk groups.

          Benefits of ASM are:
          You will have control of what disks are in what volume groups and there will be less reliance on System Administrators as compared to filesystems and raw devices.
          Automatic rebalancing when you add a disk.
          You will save on licensing if you plan to use clustered file systems. ASM is free !!
          Support from Oracle - one stop shop for any Oracle issues rather than relying on SA's or storage teams to troubleshoot issues.
          Makes administration easier, especially compared to raw devices.
          ASM can co-exist with filesystems or raw devices but I would find this pointless for the most part although there may be some exceptions.
          With 11gR2 you also have ACFS where your OCR, voting disk and binaries can sit on ACFS, although personally I would have binaries on filesystems on each host.

          Disadvantages:
          You can't backup using OS commands as can be done at filesystem level. You would need to use RMAN which could be considered an advantage in all honesty.

          I'm sure there are more of each.

          With regards to RAID level it really depends on what you want to achieve and how much you are willing to spend.

          As a general rule. redo logs should be on your fastest disks.
          Any data which will be accessed less frequently or which will be archived can be on slower disks with a lower RAID level to save money. So you can have different diskgroups on different types of RAID if this is part of your requirements.
          • 2. Re: Asm Benefits
            onedbguru
            with ASM you manage SPACE. With file systems you manage files. Big difference. Depending on your tablespaces (BIGFILE vs SMALLFILE) you can also stop worrying about filling up your data files. 8K blocks on BFTS, you get 32TB worth of storage in a single file system spread across {N} devices with {X} redundancy.

            ASM also has consistently given me a 10-15% I/O performance boost.
            • 3. Re: Asm Benefits
              Hungry DBA
              Hi Merri,

              In very simple language, ASM removes dependency of System Admin / OS Admin related to storage level activities instead as you DBA can perform these activities, once you get permissions on disks.

              * Through ASM you can create your own Diskgroup of required size with High/ Normal / External Redundancy option (same as RAID 1+0 Mirroring+Striping).
              * Ease of Management (asmcmd command prompt, you can check status of diskgroups, disks, offline/online, free_mb, total_mb)
              * Better Striping (ASM Rebalancing Feature). ASM is having different striping feature for datafiles (1M) & for control, redo files (128K).
              * Removes OS Buffering resulted in better performance.

              In 11gR2 ASM, you can also define AU (Allocation Unit) as per OLTP/OLAP Environment.

              I hope this helps you :)

              Thanks,
              Manish Nashikkar
              • 4. Re: Asm Benefits
                606331
                hi,
                please refer below links...

                http://www.oracle-base.com/articles/misc/oracle-and-raid.php
                http://en.wikipedia.org/wiki/Automatic_Storage_Management

                thanks,
                DBC,
                Sr DBA.
                • 5. Re: Asm Benefits
                  917699
                  Some of my customers implement ASM only because they have a cluster database requirement and want to use standard edition datbase licence. Oracle Standard Edition and Oracle Real Application Clusters has the restriction that Automatic Storage Management (ASM) must be used to manage all database-related files.

                  http://docs.oracle.com/cd/B28359_01/license.111/b28287/editions.htm

                  I think ASM has benefits mentions by the other users but there is from technical perspective no real need to use it since there are lots of alternatives.