{"id":15877,"date":"2014-01-07T13:08:00","date_gmt":"2014-01-07T13:08:00","guid":{"rendered":"https:\/\/aidanfinn.com\/?p=15877"},"modified":"2014-01-07T13:08:00","modified_gmt":"2014-01-07T13:08:00","slug":"hyper-v-virtual-numa-versus-dynamic-memory","status":"publish","type":"post","link":"https:\/\/aidanfinn.com\/?p=15877","title":{"rendered":"Hyper-V Virtual NUMA Versus Dynamic Memory"},"content":{"rendered":"

When you are using VMs with a large amount of memory then NUMA topology becomes important. Hyper-V can reveal the underlying physical NUMA topology to the VM so that the guest OS and NUMA-aware apps (such as SQL Server) efficiently assign memory and schedule processes to make the most of the boundaries.<\/p>\n

There is something important to note. Enabling Dynamic Memory in the settings of a VM disables virtual NUMA. That means that the vast majority of VMs will not have virtual NUMA. To squeeze the best processor\/memory performance out of larger VMs you will need to use static RAM, as noted here<\/a> under Virtual NUMA:<\/p>\n

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Virtual NUMA and Dynamic Memory features cannot be used at the same time. A virtual machine that has Dynamic Memory enabled effectively has only one virtual NUMA node, and no NUMA topology is presented to the virtual machine regardless of the virtual NUMA settings.<\/p>\n<\/blockquote>\n

So you have a balancing act to do:<\/p>\n