6 Replies Latest reply: Jan 21, 2013 1:35 PM by onedbguru RSS

    Mutliple db in ASM

    user3266490
      Hi,


      Db : 11.2.0.3
      Os :Aix

      We have 3 database under an ASM on same machine.Each db has 2 disk group's.

      Db Name :DT6
      DT6_DATAGROUP01/
      DT6_REDOGROUP01/

      Db Name :DT7
      DT7_DATAGROUP01/
      DT7_REDOGROUP01/

      Db Name :DT8
      DT8_DATAGROUP01/
      DT8_REDOGROUP01/

      How these datbase instance correctly identify the diskgroup?
      Can we use two database instance for One diskgroup?


      Thanks & Regards,
      VN
        • 1. Re: Mutliple db in ASM
          JohnWatson
          The files names identify the disk group. And yes, Oracle best practice is that all your databaes should share one disk group. And share a seciond disk group for the FRA.
          • 2. Re: Mutliple db in ASM
            user3266490
            Hi,

            Thanks for your reply.
             oracle best practice is that all your databaes should share one disk group 
            Can we restrict these things?

            For Ex: the db DT8 should use only DT8_DATAGROUP01 and DT8_REDOGROUP01.And other db instance shouldn't use those two groups.

            Thanks & Regards,
            VN
            • 3. Re: Mutliple db in ASM
              CKPT
              Can we use two database instance for One diskgroup?
              Yes, in every diskgroup lets suppose with OMF then the directory inside the Diskgroup will be created based on the DB_UNIQUE_NAME.
              Ex:
              +DG1/DT7
              +DG1/DT8

              Here DT7, DT8 are the DB_UNIQUE_NAMES of the instances.
              oracle best practice is that all your databaes should share one disk group
              Can we restrict these things?
              For Ex: the db DT8 should use  only DT8_DATAGROUP01 and DT8_REDOGROUP01.And other db instance shouldn't use those two groups.
              If you want to restrict, of course it depends on the parameters you are setting Ex: DB_CREATE_FILE_DEST. Based on the parameters files will be created if you are creating by DBCA you have options to chose the proper disk group.

              HTH.
              • 4. Re: Mutliple db in ASM
                JohnWatson
                user3266490 wrote:
                 oracle best practice is that all your databaes should share one disk group 
                Can we restrict these things?

                For Ex: the db DT8 should use only DT8_DATAGROUP01 and DT8_REDOGROUP01.And other db instance shouldn't use those two groups.
                The closest you can get is to set up access control lists within ASM.
                • 5. Re: Mutliple db in ASM
                  Levi Pereira
                  Hi,
                  How these datbase instance correctly identify the diskgroup?
                  The same way as regular filesystem. (i.e SPFILE (controlfile location) / Controlfile (datafiles/redo location).
                  Can we use two database instance for One diskgroup?
                  Yes, you can do that.
                  Can we restrict these things?

                  For Ex: the db DT8 should use only DT8_DATAGROUP01 and DT8_REDOGROUP01.And other db instance shouldn't use those two groups.
                  Yes, but it will increase administration. You will need multiples OS users and Oracle Homes.

                  "Oracle ASM File Access Control restricts the access of files to specific Oracle ASM clients that connect as SYSDBA. An Oracle ASM client is typically a database, which is identified as the user that owns the database instance home."

                  http://docs.oracle.com/cd/E11882_01/server.112/e18951/asmdiskgrps.htm#CHDIFDHD


                  About create one Diskgroup for each Database:
                  This answer will depend on of your Hardware Setup.

                  e.g
                  If on Hardware (storage) setup you have only one Array (RAID 5) and multiples Luns.

                  Then my recommendation is to create one Diskgroup, because it will end up on same disk and creating one Diskgroup will save space and reduce administration.

                  Multiple diskgroup has the benefit if you have configured different array on Storage that each Diskgroup will endup on your own Array.

                  Regards,
                  Levi Pereira
                  • 6. Re: Mutliple db in ASM
                    onedbguru
                    What you cannot control is other DBA's doing silly things like

                    ex: in DT6 -- alter tablespace add file '+DT7_DATAGROUP01'