I know this is a Windows section, but wasn't sure where else to ask.
Either way with SharePoint 2013, they say to not use Dynamic Memory as it's an unsupported configuration.
So with that, in the VM Properties, under Resource Allocation for memory, would you choose the 'Reserve all guest memory (All locked)' ?
Thanks for help on this.
"Dynamic Memory" refers to the Hyper-V feature of the same name. It's not comparable to memory reservations and there is no other equivalent of that feature in ESXi.
The article also links to a Hyper-V specific guide. I would say that the decision of whether you want to use memory reservations or not should not be driven by that statement, as it's not applicable.
I personally would avoid VM-specific memory reservations, unless you decide to unanimously reserve all memory of all guests all the time. It won't make a difference as long as your Cluster is sized accordingly to cope with host failures as well and never has to reclaim memory from guests.
Thanks for the response. So with regards to VMware then, I stumbled across this post on the forum here. This then links to a long article about all sorts of things.
About a 1/4 down this longer post, under performance, #5, it mentions having the configured memory conserved. "Distributed Cache Applications VMs should have their configured memory reserved. They heavily depend on their memory as a Cache for the entire SharePoint Farm, so they have not to participate in any memory reclaimation techniques, like ballooning."
As well they talk about it again #7, "If needed, reserve the configured memory to provide the required performance..."
A memory reservation only becomes effective when your hosts are under memory pressure and have to reclaim memory. Technically this should not happen in a correctly sized environment with DRS distributing the load across hosts.
The reservation just makes sure that all VM memory is backed by physical RAM if you ever find yourself in this situation, which you should avoid in the first place. Otherwise whether you reserve memory or not has no effect.
Therefore, I regard both points as "if needed", e.g. you know that your environment is low on physical memory.
Oh I agree in any other set up for sure. It just seems like this SharePoint Distributed Cache service, uses the extra memory that's available on the VM, but it's not considered memory pressure when it does. I guess we'll have to see how it performs when it's up an running. Thanks for the insight, much appreciated.