VMware

Numa memory question

Hi folks

I’ve read a fair few articles on this (and the changes post 6.5), and I’m either enlightened or baffled. Not sure which yet

Our hosts have 2 sockets, each with 16 physical cores, 128GB memory (4x32GB) in total for the host

We have a VM (SQLServer) which is using 10 vcpu – so that fits in a single pNUMA node, however its using 80GB memory. I think that if it was using only 64GB then it would fit with a single pNUMA, the fact that it is using 80 means that it is needing to use remote memory. which isn’t ideal

I was actually think of adding another 64GB (2x32GB) to the host giving 196GB, so 98GB per pNUMA node.

still trying to decide whether (we have Gen 10 DL380 with Intel 6130 Chips) whether that should be 3x32GB sticks per chip, or 4x32GB against one socket and 2x32GB sticks on the other socket

Does any of that make sense or have I lost whatever grasp I had on it at any point today!

thank you!



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2 Comments

  1. Most servers require the same memory layout per channel per chip. Given that you are probably going to end up with 3 memory modules per chip going with 32GB sticks.

    One item is that 6130 chips are 6 channel chips so to get the most memory bandwidth you probably want to run 6 modules per chip. So 6x16GB would be the best configuration to 192GB from a max bandwidth configuration.

    With each chip sitting in 96GB you could do a 1×10 or a 2×5 core setup as the other person suggested.

  2. For your current configuration, the best option would be to do 2 sockets with 5 cores each so you are split between the 2 NUMA nodes for the large amount of memory, which should resolve the remote memory issue, per the chart at the bottom of this article:

    [https://blogs.vmware.com/performance/2017/03/virtual-machine-vcpu-and-vnuma-rightsizing-rules-of-thumb.html](https://blogs.vmware.com/performance/2017/03/virtual-machine-vcpu-and-vnuma-rightsizing-rules-of-thumb.html)

    ​

    I can’t say for sure what is best on the memory layout for adding to your hosts. A VAR may be able to help, or others who are more familiar here. Or you could do (4×16 GB) for the same amount of memory added and keeping things balanced between the sockets.

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