Hi,
I have seen this topic brought up on various posts online, but have never seen a real answer on how to address it. In older versions of ESXi it sounds like the System Resource Reservation was tunable, but newer versions removed the capability. I mean 16GB reserved might be fine in large memory configurations, but not ideal for lab environments that are often smaller.
I have a home lab with 3 small servers running VMware ESXi, 6.7.0, 15160138. Each server has 32GB of memory in them. With 0 VM's running on a given host, there is ~17GB of memory reserved by the VMKernel. Basically about 50% of the memory.
I have a 6.0 installation on a host that has numerous VM's running and the VMKernel is only reserved ~3GB of memory.
Here's what Vcenter shows for "System Resource Reservation" on a host:
Here's what Vcenter Performance Monitor shows for VMKernel consumed memory for a given host with 0 VM's running. It stays flat lined around 16GB:
Here is what "esxtop" shows from the host. You can see vmk using ~16GB of memory with 0 VM's running:
So trying to figure out ESXi 6.7 is reserving so much memory for VMKernel in this case. I thought these small servers would be good for a home lab, but they aren't so cost effective if 50% of the memory is lost to the VMKernel.
ESXi 6.0 is only using less than 3GB of memory for VMkernel on another installation I have with numerous VM's running
The major difference between the ESXi 6.7 and 6.0 installation in my case is that Vsan is being used on the ESXi 6.7 cluster where as the 6.0 cluster uses a shared FC VMFS datastore.
I would like to understand if this is simply a hard coded setting in ESXi 6.7 that all hosts reserve a minimum of 16GB of memory for a host, or perhaps ESXi is calculating the reservation incorrectly for some reason. Then obviously I want to know if there is a way to modify the VMKernel resource reservation to something more reasonable like 3GB.
I have seen numerous posts on this with no real answer.
Thanks,
Steve....