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Memory slow to consume in VM with large application RRS feed

  • General discussion

  • We have a couple of VM  machines allocated with high quantities of RAM (20-32gb).  On two separate instances I have noticed that memory is not allocated to a program immediately.  Instead the large application will commit a significant "chunk" of available memory (12-14gb) and will slowly climb ~256k\second to consume the rest of the needed Memory.  Information on the two separate instances are below:

    #1: VM running Server 2008 R2 with 32gb of allocated RAM.  The VM is for development purposes and has SQL Server 2008 configured to use ~30gb of RAM as a max.  When the server gets booted the SQL Server will used ~14gb of RAM.  It will then climb overnight to its 30gb maximum.

    #2: VM running Server 2008 R2 with 28gb of allocated RAM.  The VM is running an internal devloped application which requires ~20gb RAM.  When the application is loaded it will allocate the program ~16gb of RAM.  It then proceeds to climb slowly until it reaches its expected 20gb limit.

    I have searched the knowledge base and web to no avail.  The memory that is not being utilized by the application is then being used by the System Cache. RamMap reveals that it is for 'Mapped File'.  As the programs SLOWLY climb to there expected RAM utilization, the Mapped File System Cache decreases.

    Can someone please explain this behaviour to me?  Why isn't this memory being immediately available to the requesting programs? Tips? Solutions?

    Thanks in advance for your help,

    -Dan

     

    Thursday, April 14, 2011 7:10 PM