Always create a Resource Pool?

[HenrikElm]

One of our technichians was told at a VMWare course he attended that you should always create a Top Resource Pool with a RAM limit about 10-20 MB less than your hosts physical RAM, in order to give it some headroom.

?????????????

I have never heard this before or seen any papers or VMWorld sessions about this. I simply believe it to be a bad practice? As I understand it SYSTEM already has a reservation in place? Anyone care to comment on this practice?

/Henrik

[NTurnbull]

Hi Henrik, must say that I've never heard of this, the cluster is the root resource pool. Besides having ~10/20MB RAM for 'head room' isn't really going to do anything if all your other RAM is being used by vm's!

Thanks,

Neil

[HenrikElm]

Yes, I know.. Very strange recommendation.. I will tell them that this must be some misunderstanding and should NOT be used as a best practice.

/Henrik

[NTurnbull]

I would agree, it doesn't really serve any function - I mean let's be honest here, your running a host with 32GB of RAM and say 30 vm's - is ~10/20MB of RAM 'head room' going to do anything? Let alone if you actually get into that senario and your hosts are that loaded that HA wouldn't do anything due to insufficent resources!

Thanks,

Neil

[HenrikElm]

Exactly. And when you adjust physical RAM in hosts you need to reconfigure the pool to make use of it.. I see all kinds of trouble.. Bad teacher simply put..

/Henrik