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Understanding Maximum Server Memory in SQL SERVER

  • December 27, 2023 at 12:00 am

    #4338038

    Comments posted to this topic are about the item Understanding Maximum Server Memory in SQL SERVER

  • December 27, 2023 at 8:45 pm

    #4353239

    After reading this article, I'm left with more questions.

    What I took away was "It is important" and "set it to 75%".

    But I wonder:

    -why 75%?   is this MSFT guidelines on this?   why not 90% if you have a lot of memory?

    -are there symptoms if it is set too low?  too high?

    -How do you calculate how much the operating system needs?

    -where would you go to monitor it, to see if the change is effective in improving performance if you have to justify to your boss the expense of more memory, for example?

    THANKS

  • December 28, 2023 at 6:59 pm

    #4353693

    Great job on the article, really bad job on the 75% recommendation.

    If there is 32 GB of RAM, then 75% is probably too high.  If there is 32TB of RAM, then 75% is too low.  Yes, I have multiple servers with 32 TB of RAM.

    This article provides a better calculation than blindly picking 75%

    https://www.sqlskills.com/blogs/jonathan/how-much-memory-does-my-sql-server-actually-need/

    Michael L John
    If you assassinate a DBA, would you pull a trigger?
    To properly post on a forum:
    http://www.sqlservercentral.com/articles/61537/

  • December 28, 2023 at 9:10 pm

    #4353730

    I've been setting up bare metal SQL servers since SQL 2000, and I always set the max memory to the total memory - 4GB reserved for the operating system. I check the free memory from time to time to make sure I'm not getting into the swap file. I think this article is completely incorrect, and they don't back up their 75% claim with any evidence.

  • December 28, 2023 at 9:41 pm

    #4353738

    Brain2000 wrote:

    I've been setting up bare metal SQL servers since SQL 2000, and I always set the max memory to the total memory - 4GB reserved for the operating system. I check the free memory from time to time to make sure I'm not getting into the swap file. I think this article is completely incorrect, and they don't back up their 75% claim with any evidence.

    4 GB is may not a good value.  If there are other services running these must be considered in the calculation.

    Michael L John
    If you assassinate a DBA, would you pull a trigger?
    To properly post on a forum:
    http://www.sqlservercentral.com/articles/61537/

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