Lock Pages in Memory setting for 64-bit systems

  • Now this is one case where I have heard that Lock Pages in Memory can get you in trouble. If you have Virtual Servers with overcommit enabled on the RAM.

    I'm not a virtualization expert (and perhaps you are not using overcommit RAM on your virtual SQL Servers). Has anyone else heard the same thing? What are the pros and cons of using Lock Pages in Memory with Virtual Servers? (For that matter, how does it work when you have virtual servers?)

  • Virtual servers with overcommit and SQL Server on them is going to get you in trouble anyway, locked pages or not.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • Server Configuration

    ----------------------

    Windows 2003 R2 Enterprise Edition 64 bit SP2

    RAM - 96 GB

    SQL version - SQL Server 2008 R2 SP2 Enterprise Edition 64 bit

    Memory allocated to SQL Server -- min = 0, Max = 86 GB

    Checked in logs found Locked pages are enabled.

    When I check in the Task Manager--PF Usage it is 92.3 GB (consistently) due to it the applications are running slow.

    Checked in Task Manager- Processes--sqlservr.exe is using 0.7 GB of memory & calculated all the processes it is not taking more than 15 GB of memory.

    I still cant figure out which application\program is using the rest of the memory.

    Please suggest.

  • Don't use Task Manager to check SQL's memory usage. It can report a completely incorrect figure. Use perfmon.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • Please let me know what counters need to monitored to find the physical memory usage?

  • Results after executing DMV "sys.dm_os_process_memory"

    physical_memory_in_use_kb = 93631444 KB

    locked_page_allocations_kb = 92303888 KB

    Does it mean 92303888 KB is locked for OS?

  • Total server memory. It's a SQL counter.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • The counter's graph is near to 100%

  • surilds (1/22/2013)


    The counter's graph is near to 100%

    Total server memory is not measured in %, it's measured in KB

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • surilds (1/22/2013)


    Results after executing DMV "sys.dm_os_process_memory"

    physical_memory_in_use_kb = 93631444 KB

    locked_page_allocations_kb = 92303888 KB

    Does it mean 92303888 KB is locked for OS?

    No. That DMV measure's SQL's memory usage.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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