What is the reasoning behind allocating the OS 1GB for each 4GB of RAM?

All we need is an easy explanation of the problem, so here it is.


Let us now briefly look at the techniques to size the memory.

1 GB of memory reserved for Operating System 1 GB each for every 4 GB
of RAM after the initial 4 GB, up to 16 GB of RAM 1 GB each for every
8 GB in more than 16 GB of RAM For example, if you have a 32 GB RAM
Database Server, then memory to be given to Operating System would be

1 GB, the minimum allocation

  • 3 GB, since 16 GB – 4 GB = 12 GB; 12 GB divided by 4 GB (each 4 GB gets 1 GB) is 3GB.
  • 2 GB, as 32 GB – 16 GB = 16 GB; 16 divided by 8 (each 8 GB after 16 GB gets 1 GB) is 2 GB So, in total, for a server with 32 GB of RAM, 7
    GB will be reserved for the Operating System. This is the maximum
    memory allocated to SQL Server should be 25 GB. Similarly, for a 64 GB
    Server, 10 GB should be reserved for the Operating System & 54 GB
    should be allocated for SQL Server.

What is the reasoning behind allocating the OS 1GB for each 4GB of RAM?

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

I’d say ask the author, he’s got quite a complicated formula for calculating Memory allocation, IMO.

There’s a bunch of rule of thumbs out there on how much Memory to leave the OS hosting a SQL Server instance – they’re all pretty good. Brent Ozar’s starter rule of thumb is to allocate 4 GB or 10% of the total Memory, whichever is larger, as discussed in Memory Dangerously Low or Max Memory Too High. I usually follow this rule myself and haven’t had any issues with it.

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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