5 Replies Latest reply: Mar 26, 2013 9:22 AM by KR10822864 RSS

    ASMM enabled when memory_target>0 but sga/pga_target=0 ?

    907116
      If MEMORY_TARGET is set but sga_target and pga_aggregate_target are not set (zero) then is ASMM (Automatic Shared Memory Management) enabled ?
      Meaning does it dynamically redistribute memory between the internal componets of the sga (db cache, shared pool, large pool) and pga (sort area,..) as needed ? Or does it require sga_target and pga_aggregate_target to be > 0 for that to happen ?
        • 1. Re: ASMM enabled when memory_target>0 but sga/pga_target=0 ?
          JohnWatson
          Percy Mistry wrote:
          If MEMORY_TARGET is set but sga_target and pga_aggregate_target are not set (zero) then is ASMM (Automatic Shared Memory Management) enabled ?
          Yes
          Meaning does it dynamically redistribute memory between the internal componets of the sga (db cache, shared pool, large pool) and pga (sort area,..) as needed ?
          Yes
          Or does it require sga_target and pga_aggregate_target to be > 0 for that to happen ?
          No
          • 2. Re: ASMM enabled when memory_target>0 but sga/pga_target=0 ?
            VamshiDamidi
            ASSM means all pools managment minus PGA which mean you have to manually specify the PGA

            Memory_target > 0 with SGA and PGA targets being 0 means ASMM + pGA memory managements

            Let me know if you have any concerns.

            Thanks,
            Vamshi .D
            • 3. Re: ASMM enabled when memory_target>0 but sga/pga_target=0 ?
              jgarry
              VamshiDamidi wrote:
              ASSM means all pools managment minus PGA which mean you have to manually specify the PGA
              Automatic Segment Space Management. I know, acronym namespace too crowded. But then again, one misplaced comma in code can ruin your whole db.
              • 4. Re: ASMM enabled when memory_target>0 but sga/pga_target=0 ?
                907116
                VamshiDamidi wrote:
                ASSM means all pools managment minus PGA which mean you have to manually specify the PGA

                Memory_target > 0 with SGA and PGA targets being 0 means ASMM + pGA memory managements
                Are you saying it will manage SGA pools but not PGA work areas, unless pga_aggregate_target is specified ? Even though workarea_size_policy would still be auto(default) ? I am curious what would be the default memory distribution for the pga work areas in that case.
                • 5. Re: ASMM enabled when memory_target>0 but sga/pga_target=0 ?
                  KR10822864
                  according to oracle documentaion..

                  if sga_target, sga_max_size and pga_aggregate_target are set to 0, then 50 to 60% of memory mentioned in memory_target is allocated to SGA and rest is kept for PGA.
                  if sga_target and pga_aggregate_target are set to non-zero values, then these values will be considered minimum values.
                  if sga_target is set to non zero value and pga_aggregate_target is not set. eventhough these values will be auto-tuned and pga_aggregate_target will be initialized with value of memory_target and sga_target.
                  if pga_aggregate_target is set and sga_target is not set eventhough those both parameters will be auto-tuned the sga_target will be initialized to a value of memory_target and pga_aggregate_target.

                  http://docs.oracle.com/cd/B28359_01/server.111/b28320/toc.htm