SQL Server Performance

using the /3GB switch and the /USERVA

Discussion in 'SQL Server 2005 Performance Tuning for DBAs' started by avipenina, Sep 5, 2007.

  1. avipenina New Member

    Hi,
    can you Plz set my mind about this /3GB switch issue.
    I've few SQL Server 2005 STD that run on Windows Server 2003 STD SP2 that have 2GB,3GB,4GB and i relay want to know if i can use the /3GB switch on which server that have the enough MEM to use it and also what about the /USERVA do i need to use it?
    i can say that all those server a dedicated SQL Server and not Domain Controller or any thing else.
  2. satya Moderator

    If AWE is not enabled, SQL Server can only see up to 2GB. However, if you enable /3GB in boot.ini, SQL Server can then see up to 3GB. SQL Server will only take advantage of the 8GB memory if you use /PAE, /3GB in boot.ini, and enable AWE. Make sure you set Max memory to about 6.5GB, or so.
    The following article would be a good resource to understand SQL Server memory usage: "How to configure memory for more than 2GB in SQL Server".
    http://sqlserver-qa.net/blogs/perftune/archive/2007/08/23/1678.aspx and further by default, no user, not even Administrator, is granted the necessary privilege. The "Lock Pages in Memory" user right can be assigned by using Group Policy Editor (gpedit.msc), which hosts the Group Policy MMC snap-in.
    ref http://msdn2.microsoft.com/en-us/library/ms190730.aspx
  3. avipenina New Member

    as i understand if i don't use the /3GB switch on machine that have 3GB or 4GB mem the OS take to itself 2GB of the 3GB or 4GB that available in the physical memory.
    but if i use the /3GB switch that the OS can't take more then 1GB to itself from the physical memory?
  4. avipenina New Member

    Hi,
    server 2K3 STD and SQL 2K5 STD with 3GB of MEM , should i use the /3GB switch in the boot.ini for server with 3GB MEM?
    i know that it will be good to turn on the /3GB on server that have 4GB but my question is on server that have 3GB, and it's a dedicated server for SQL.
  5. satya Moderator

    If you are using SQL 2005 then no need to setup such switches, best to check whether system is using available memory or not use PERFMON (SYSMON) for memory counters.
  6. avipenina New Member

    what is the best way to see how much memory only my system take,without the sql and other applications.
    Thx
  7. satya Moderator

  8. IDTX2 New Member

    [quote user="satya"]
    If you are using SQL 2005 then no need to setup such switches, best to check whether system is using available memory or not use PERFMON (SYSMON) for memory counters.
    [/quote]
    Just for clarification, I though SQL 2005 32 bit could still only use 2GB of memory without playing with the switches in the boot.ini? Is this correct?
  9. satya Moderator

    Yes it can use,
    • Standard Edition x86 = os limit
      • Standard Edition x64 = 32TB
  10. IDTX2 New Member

    [quote user="satya"]
    Yes it can use,
    • Standard Edition x86 = os limit
      • Standard Edition x64 = 32TB
      [/quote]
      This link to BOL:
      http://msdn2.microsoft.com/en-us/library/ms187499.aspx
      Seems to indicate the /3GB switch would be required on 32bit systems for SQL Server to use more than 2GB of the first 4GB and AWE would be required to address memory above 4GB (for buffer pool pages only) if available on the server.

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