Notes.ini Entry


Name:
    Aix_Limit_Shm_Segments

Syntax
    Aix_Limit_Shm_Segments=Number

Applies to:
    Servers - AIX Only

Add-on:

    First Release:
      7.0

    Obsolete since:

      Category:
        Memory, Shared Memory

      Default:
        None

      UI equivalent:
        None

      Description:
      SPR# XJXJ6RW8VF - The Notes.ini variable AixLimitShmSegments, is to be used in place of the Notes.ini variable ConstrainedSHMSizeMB to ensure entire segments are specified for shared memory.

      The lower limit is 3 and the current upper limit is 10. The maximum number of shared memory segments when using the AIX Large Memory Model is 8. The maximum number of shared memory segments when using the AIX Very Large Memory Model is 10.

      Future releases of Domino may allow for a maximum of 11 shared memory segments.

      Fixed in 7.0.2 FP1 release

      notes.ini AIX_LIMIT_SHM_SEGMENTS helps to manage the memory usage of Domino running on AIX.

      Use AIX_LIMIT_SHM_SEGMENTS to ensure the Domino instance has access to whole segments of shared memory. AIX memory segments have a maximum value of 256 Megabytes. The value used should be between 3 and 10.

      The Domino server must be restarted after modifying this setting.

      Restrictions:
      This setting applies only to the AIX operating system.

      Domino 8 and higher versions now implement a lower, more effective limit to the size of the UBM in order to accommodate larger systems. Testing and performance data from the field indicates that a UBM limit of 512 MB is the optimum size limit on most platforms, allowing Domino to realize efficient disk I/O when accessing database structures on disk. Values higher than this have been found to result in increased memory usage without significant performance improvements.

      The Domino 8 server enforces this limit by default with no additional notes.ini file parameters required. Domino will still honor the setting NSF_BUFFER_POOL_SIZE_MB (as well as related parameters) on upgraded servers, which can be used to configure the UBM to be larger than 512 MB if necessary. The default limits depend on platform, which are listed in the table below:


      Operating System
      Domino 8 32-bit
      Default Maximum UBM Size
      Domino 8 64-bit
      Default Maximum UBM Size
      Domino 8.5 64-bit
      Default Maximum UBM Size
      Windows32, Linux, AIX, Solaris, i5/OS
      512 MB
      1024 MB
      1024 MB
      zOS
      400 MB
      n/a
      n/a
      zLinux
      400 MB
      n/a
      1024 MB

      In essence, this new Domino 8 behavior obsoletes the need to use any additional INI parameters to scale the UBM size. This includes use of the INI parameters listed below:

      PercentAvailSysResources
      ConstrainedSHM, ConstrainedSHMSizeMB
      MEMAddressableMem, MEMAddressableMemSizeMB
      MEM_EnablePreAlloc, MEM_EnableSubAlloc


      For more information on these parameters as well as sizing recommendations on Domino 6 and Domino 7, refer to "Recommendations for Setting NSF_BUFFER_POOL_SIZE" (#1286171) , which discusses considerations about these parameters on systems with more than 2 GB of RAM.

      Note: ConstrainedSHM can still be used to control the overall amount of shared memory usage, but is not needed in Domino 8 specifically to limit the maximum UBM size. If a change to the UBM size is deemed by IBM Support to be necessary, it is recommended to use the NSF_BUFFER_POOL_SIZE_MB parameter.