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SSAS Memory Settings

  • November 11, 2015 at 7:36 am

    #309565

    Hello,

    We have hit a memory problem on an analysis server (not production).

    We have:

    - 72GB installed

    - 50GB allocated to SQL SVC

    MSMDRSV.ini is currently:

    - TotalLimit = 80

    - HardLimit = 0

    - LowLimit = 65

    this means that SSAS will use 80% of total memory used by SSAS until it starts to trim/clean usage....and 90% will be used for the hard limit....correct?

    if i want to keep the 50GB for SQL and try to limit SSAS to <15GB could i use the settings:

    - TotalLimit = 25

    - HardLimit = 20

    - LowLimit = 10

    this to me states that:

    - SSAS has an upper limit of 25% of total system memory used, and once reached, sessions may be killed to free up memory

    - SSAS has a soft upper limit of 20% of total system memory used, and once reached, it will start to be more aggressive to free up memory

    - SSAS has a low limit of 10% of total system memory free, and once it is below this it wll start to free up cache space and remove old calculations

    am i correct in all this?

    thanks

  • November 11, 2015 at 7:50 am

    #1839110

    You could go very specific to the byte level

    Values <=100 are defined as percentages

    Values > 100 are defined as a fixed amounts in bytes

    So if you ideally wanted to limit SSAS to 10GB, you would enter a value of 10,737,418,240 (1024 (b) x 1024 (kb) x 1024 (mb) x 10 (gb))

  • November 11, 2015 at 7:50 am

    #1839111

    sorry....total must be less than hard....so:

    HARD = 25

    TOTAL = 20

    LOW = 10

  • November 11, 2015 at 7:54 am

    #1839113

    ooh....so i will convert my percentages into numbers

    do the percentages look OK as a starting point?

    I cant take memory away from SQL but i can play with SSAS as its only for basic overnight processing....but currently has all the memory SQL is not using which is just silly!

    many thanks

  • November 11, 2015 at 7:59 am

    #1839115

    You have 22GB to play with, generally I now leave around 10% for the OS, so that eats 7GB out of your allowance, so you have 15GB to play with.

    I would say set low to 0bytes, total to 10GB and hard to 12GB and see how it goes.

    You might have to tweak further, especially if your SQL instance has lots of linked servers, sp_oa*** calls, extended stored proc calls etc as they all use memory from outside of the 50GB you have allocated to SQL

  • November 11, 2015 at 8:05 am

    #1839121

    thanks anthony

    i have used 15/12/0 and will see how it goes

    we have very basic queries being run by analysts, no extended sp's and some basic SSIS packages and a SSAS cube around 20GB

    lets see how it goes 🙂

    please mark as answered

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