When VMware ESXi NVMe memory Tiering Meets vGPU: What You Need to Know

A few weeks ago, I did a research with Leee Jeffries for GO‑EUC on NVMe memory tiering versus traditional swap in VMware ESXi.

VMware ESXi Memory Management Reimagined: NVMe Tiering vs Traditional Swap | GO-EUC

The article sparked some great discussions and there is an important caveat when it comes to vGPU desktops that I want to highlight.

vGPU Desktops Always Need Full DRAM

Here’s the thing that often trips people up: every VM with a vGPU requires all of its RAM to be reserved in physical DRAM before it can start. If the host cannot satisfy that reservation, the VM will not boot.

Some assume that memory tiering somehow adds extra usable RAM because the host reports more “available” memory. That is not the case.

The caveat: the added NVMe capacity cannot be used to satisfy the DRAM reservation. So adding NVME memory tiering does not provide extra memory for vGPU enabled VM's

as soon as the DRAM runs out, you will simply get the error:

"The host does not have sufficient memory resources to satisfy the reservation"

Also, because all their memory is pinned in DRAM, so tiering (offloading to NVMe) simply does not apply.

This is a "limitation" you need to consider.

Where NVMe Tiering Actually Adds Value

NVMe memory tiering shines in workloads that do not require full memory reservation, such as:

• Non-GPU VDI desktops

• RDSH hosts

• App servers, brokers, and infrastructure VMs

• Any VM where memory usage is variable

  
  

Especially in environments with many idle or inactive sessions, tiering allows cold pages to spill to NVMe, freeing DRAM. This can reduce memory pressure, improve host efficiency, and increase consolidation ratios.

However, testing is crucial to ensure expected performance under load.

If a host runs only vGPU desktops, tiering provides minimal benefits. It is not useless, but the gains are small unless non-GPU VMs are also sharing the host.

My Takeaways

From my perspective:

• vGPU desktops always require full DRAM reservation. NVMe tiering capacity cannot be used for that reservation.

• NVMe tiering is excellent for non-GPU workloads, especially with many idle sessions. That is where it really pays off.

• Pure GPU hosts see limited value from tiering.

  
  

The key is to treat NVMe tiering as a memory efficiency tool. In short: NVMe tiering is powerful, but you need to understand where it works, avoid assuming it reduces your DRAM footprint, and always validate your design through testing.