Managing Memory

  • Hi,

    I upgraded a server with 4 CPU’s and 2GB of RAM with an additional 2 GB of RAM

    The server has now 4GB RAM (4096 MB)

    What are the proper switches to use in the Boot.ini?

    Do I have to use /3GB or /PAE or both or none?

    And what’s the best thing to do in SQL2K enable the AWE Enabled switch or not?

    Please some advise and explanations.

  • Hey Ludo,

    The /3GB switch is all you need when your server has 4GB of RAM. Make sure that it is the Enterprise edition and not Standard. The standard edition can only use up to 2GB of RAM. The /PAE switch is only needed when you need to go above 4GB.

    Check out this link at SQL Server Performance for more details:

    http://www.sql-server-performance.com/awe_memory.asp

    JM

  • So if we do use the /PAE and only have 4GB, is that ignored or should we remove it?

    Darren


    Darren

  • What if you want to use more than 4GB? I've got my switches set correctly, set AWE enabled to true, granted privileges to lock pages in memory and performance went into the tank, 5 miunte jobs now took 3 hours. I removed the privilege and siabled AWE until we can get this figured out. Anyone have any experience with going above 4GB? What did you do to get it to work correctly?

    Terry


    Terry

  • We have a server with 6GB of RAM. I have the /3GB and /PAE switches set in the boot.ini. The server has the "awe enabled" option set to ON. The "max server memory" is set to 5GB (5000 MB).

    -Dan


    -Dan

  • Hi,

    From how I understand things, the PAE switch is used on win2k Advanced if you have over 4 GB of ram without windows will not see or use more than 4 GB of ram without it. (Although I have come across issues installing and uninstalling applications with it and am not going to get into that.)

    The 3GB switch is used to separate the amount of memory reserved for the os and applications/services on the server. If you have 4 GB of ram, it will reserve 1 gb for the os, and the other 3 will be used for applications/services.

    The AWE switch is used for SQL Server to see more than 4 gb of ram. The curve with AWE (SQL 2k)is that you cannot use dynamic memory allocation. You must specify the min and max of memory that you want SQL to use. So Lundo, to answer your question, I would use the 3GB switch only. The awe switch will not do much for you and it does require more administration and monitoring initially to achieve the best performance with it.

    Tom

  • Dan, Any adverse impact on performance? I set my max to 4.8 gig and for some reason the OS reserved memory got locked up and processing just died. Are there any other config values, either within SQL or at the OS level, that need to me changed?

    Terry


    Terry

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