SQL memory config - AWE

  • I have a cluster with 16 gb RAM on each server, one instance on each server and no other applications on either server.  Do I set the max server memory to 6 gig, 7 gig or  8 gig for each server?  I would think 7 gig, if I had a failover I would have 7+7 +2 (for the OS).  Do I need to consider 2 gig for the OS when setting max server memory?

     

    Also, does AWE need to be set manually after each boot.  I ask this because BOL (AWE Enabled Option) states it is strongly recommended to set max server memory EACH TIME AWE is enabled.

     

    thanks

  • Based on your post, you are configuring a 2-node Active/Active cluster.

    Yes, you need to consider the ram that OS needs. But the SQL server MAX RAM does not need to be equally divided. If the load of the two sql server is pretty different, you can set up the ram differently, say 10GB for server A and 4 GB for server B.

     

    I don't think you need to set AWE manually after each reboot. The settings are persisted. The BOL's meaning is that you need to setup MAX ram for SQL server if AWE is enabled, otherwise SQL sever will grab all RAM except that leaving 128MB to OS.

     

     

     

  • Yeap ur right, don't use the /3Gb switch as this will leave 1GB for the OS.  Put the /PAE switch in the boot.ini of each server and enable AWE. 

     

    Conffigure each server to use 7GB for max server memory if the load is the same or otherwise balance it as per your requirements.  So if u do have failover then both instances can run smoothly.

    HAPPY DAYS!!

  • Actually the OS does not need more thatn 1 gig correct, thus the 3 gb switch?  In that case I would use the 3gb switch, and if dividing the RAM equally between servers, designate 7.5 gigs to server A and 7.5 gigs to server B.  Is that correct?

    thanks for the feedback

  • The general rule I follow is if a server has between 3GB and 16GB use the /3Gb switch and the /PAE switch in the boot.ini. 

    The /3Gb switch will leave 1GB for the OS and the /PAE switch will allow the system to address the memory over 4GB when AWE is enabled.

    If a server has 16GB or over then don't use the /3Gb switch as the OS needs 2GB to do its thing to address the 16Gb+ memory. 

    So with ur environment I would put the /PAE switch in the boot.ini and set the max server memory to 7GB for each instance.  Leave out the 3GB switch for now and see how it goes bcause if memory does become resource intensive I would bump the memory in each box rather than putting the /3Gb switch in.

    Hope that makes sense!!

     

    HAPPY DAYS!!!

  • Is there any point in turning on AWE on a box that has only 3GB of memory?

    FisherDad

  • I guess you are not using 64 bit... just checking because AWE and /3GB have no meaning then...

    So 32 bit.

    I guess you're on Windows 2003 with 16GB RAM.

    Question for all:

    Does SQL use the 32 Gb "seen" on Win2003 enterpise?

    Or is it limited to the "old" 8GB "seen" on Windows 2000 advanced.

    I've not yet seen high-end Win 2003 boxes to see for myself...

    I say this because if you set 7Gb per instance, but you can only "see" 8GB, you could have interesting times during a failover...

     

  • This is a 32 bit Win Enterprise 2003 Server with dual 3.2GH Processors acting as 4 and _3_ Gig of memory.  No failover involved.  CPU usage is generally light but has its moments.  From what little reading I've done it was not clear if there would be any benefit in turning AWE on.  We are running Reporting Services, SQL DB and Web sites off this box with < 500 users.  We are starting to have large queries searching historical accounting data.  This will be from a limited number of users. 

    FisherDad

  • The first post says 16Gb RAM.

    And a different name of poster.

    So, which server config question should I try and answer?

  • I think 'Veteran' was refering to the original question.  I asked a separate one which I should have started in a new topic I guess sorry for the confusion.  To repeat:

      Is there any point in turning on AWE on a box that has only 3GB of memory?

     This is a 32 bit Win Enterprise 2003 Server with dual 3.2GH Processors acting as 4 procs and has _3_ Gig of memory.  No failover involved.  CPU usage is generally light but has its moments.  From what little reading I've done it was not clear if there would be any benefit in turning AWE on.  We are running Reporting Services, SQL DB and Web sites off this box with < 500 users.  We are starting to have large queries searching historical accounting data.  This will be from a limited number of users. 


    FisherDad

  • No. AWE is usually used when you have more than 4GB RAM.

     

  • Even if you set AWE, it will be ignored by SQL if you less than 3GB RAM anyway (from BOL)

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