Hyper-V memory oversubscription

Welcome back to my third article, I hope these provide some useful information. This posting is based around my observations of the differences in how vSphere and Hyper-V manage memory on the host. Without further rambling, let’s get started.

Hyper-V handles memory in a noticeably different way than vSphere does. This has taken me some getting used to but the largest take away is that it does not overcommit memory. Microsoft uses the term Dynamic Memory for their version, and based on my observations that is a good term for it.

Memory over allocation in vSphere is handled through the VMTools and the balloon driver in instances of the memory allocation actually being utilized. This historically, to my understanding, results in paging to disk when recovered memory isn’t adequate for the needs to be met. This is where Dynamic Memory kind of breaks my brain. Unlike vSphere, which more or less just assumes you will overcommit at some point, you need to explicitly enable this functionality. It’s not complicated, just not something you might think to do when coming from a VMware environment.
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