5 Replies Latest reply: Sep 6, 2012 4:59 AM by Spugna RSS

    Configuring Database running on server with 256 cpu

    Spugna
      Hi all,

      we have a rac installation 11.2.0.2 on Solaris 10.
      The servers are 2 and a short configuration is:

      SQL> show parameter cpu_count
      NAME TYPE VALUE
      ------------------------------------ ----------- ------------------------------
      cpu_count integer 256

      psrinfo | wc -l
      *256*
      prtconf | grep "Memory"
      Memory size: *130784 Megabytes*
      psrinfo -pv
      The physical processor has 64 virtual processors (0-63)
      UltraSPARC-T2+ (chipid 0, clock 1414 MHz)
      The physical processor has 64 virtual processors (64-127)
      UltraSPARC-T2+ (chipid 1, clock 1414 MHz)
      The physical processor has 64 virtual processors (128-191)
      UltraSPARC-T2+ (chipid 2, clock 1414 MHz)
      The physical processor has 64 virtual processors (192-255)
      UltraSPARC-T2+ (chipid 3, clock 1414 MHz)

      There are a lot of parameters that Oracle automatcally design based on the number of cpu.
      In my case this number is too high.

      For example, normally db_cache_size=4Mb*cpu, in this case the result is 1G of db_cache_size.

      The plan is to create many databases on this rac so the question is:

      There is a way to design or to tell to oracle a different number of cpu?
      and generally....
      Do you have some advices about how it's possibile to configure a so powerfull machine that is running a lot of instances?


      Thanks in advance

      Edited by: Spugna on May 7, 2012 3:01 AM
        • 1. Re: Configuring Database running on server with 256 cpu
          Svetoslav Gyurov
          Hi Spugna,

          Sure as long as you're using Oracle 11g you could use Instance Caging to limit every database CPU usage. Although this is more applicable for single server database or RAC One Node I see no reason why not to use it with RAC. Look here for more information:
          http://docs.oracle.com/cd/E14072_01/server.112/e10595/dbrm007.htm

          You could also consider consolidation of these different database within one big database if it's possible and there are no application dependencies ?


          Regards,
          Sve
          • 2. Re: Configuring Database running on server with 256 cpu
            sybrand_b
            The plan is to create many databases on this rac so the question is
            The question is who planned this. It is just plain wrong to have many databases on one server.
            Oracle has the capability to have multiple schemas in one database, so having 'many' databases looks like your site only knows sqlserver and doesn't know Oracle.
            Your plan is not going to work, ever.

            -------------
            Sybrand Bakker
            Senior Oracle DBA
            • 3. Re: Configuring Database running on server with 256 cpu
              Spugna
              I would agree with you if the server wasn't so powerful, and users and application running against it wouldn't be so many...
              It's not easy to manage with only one instance per node more than 1000 schemas and 100000 connections...
              Application from different customers (worldwide), with different developers, with different ideas, with very differetn logic.

              One big database with a sga about 120Gb is not the answer.

              I understand that for a dba usually it's easier one instance per machine (and a good way to use resource of the machine),
              but this is not our case.

              About you idea I can add that on the server there is a big instance that should be the instance reserver for all that small applications
              that need only one schema. So in a little way we are starting to consolidate.

              Anyway thank you for the answer.

              Ciao
              • 4. Re: Configuring Database running on server with 256 cpu
                Paulie
                >

                I understand that for a dba usually it's easier one instance per machine (and a good way to use resource of the machine),
                but this is not our case.
                About you idea I can add that on the server there is a big instance that should be the instance reserver for all that small applications
                that need only one schema. So in a little way we are starting to consolidate.
                Have you considered VM's?

                That's the way people consolidate with machines with 256 cpus, most of the time. How many
                schemas do you have? The things you can do with VM's these days are amazing.


                You should never have more than 1 db on 1 server OR VM. If one of your systems fails
                in a monolithic system, you could bring down all your schemas.

                Paul...

                Edited by: Paulie on 07-May-2012 16:31
                • 5. Re: Configuring Database running on server with 256 cpu
                  Spugna
                  I agree with VM.

                  I have found that all my performance problems are because of the machine.

                  Migration from fast single threaded CPU machine to CMT UltraSPARC T1 and T2 results in increased CPU reporting and [ID 781763.1]


                  thanks for everything