Buffer pool memory is higher than max server memory

  • I have set the max server memory to 1024

    exec sp_configure

    max server memory (MB)16214748364710241024

    But my buffer pool is still using more than 1GB of memory

    DBCC MEMORYSTATUS

    MEMORYCLERK_SQLBUFFERPOOL

    VM Reserved1658368

    VM Committed1061976

    The server had been rebooted. Am I missing something here?

  • Edit..

    Looks OK. What is telling you it's wrong?

    VM Committed 1061976

    1061976 kB = 1037 MB, which is close enough to 1024 to be rounding or a 1000/1024 division issue.

    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
  • Do you mean the MAX SERVER MEMORY value only affects the VM committed, but not the VM reserved? This seems a bit puzzling...

  • https://support.microsoft.com/en-us/kb/907877

    VM Reserved: This value shows the overall amount of virtual address space (VAS) that SQL Server has reserved.

    VM Committed: This value shows the overall amount of VAS that SQL Server has committed. VAS that is committed has been associated with physical memory.

    Reserved doesn't mean used and it's not physical memorym it's virtual address space.

    To give you an idea, any 64-bit Windows machine has multiple TB of virtual address space which applications can reserve any amount of. They obviously don't have that as physical memory though, so applications can't commit more than the server has as physical (or more than the application is allowed to use)

    If you're not sure the interaction between virtual memory and physical memory, there are some really, really good videos by Mark Russinovich. Google should turn them up, they require a few watchings to understand properly though.

    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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