resource pools creation

[willstej83]

I would like to start configuring resource pools in my environment, but struggle to understand how to configure them for certain VM's. How to size the pool right and what application servers to put where. Does anyone have some links for GOOD articles on resource pools...not that just explain what they are but really how to leverage them and configure them.

[pratjain]

These links should be useful

http://pubs.vmware.com/vsphere-51/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-51-resourc...

http://vmtoday.com/2012/03/vmware-vsphere-resource-pools-resource-allocation-revisited/

http://frankdenneman.nl/2010/05/18/resource-pools-memory-reservations/

[willstej83]

So I have created a resource pool and called it "SQLServers" I want to pool all SQL Servers together so they can use each others resources when needed. I set the shares to high and put my first SQL server in the pool, then I try to add another one and get a:

"Resource Settings Warning"

The memory resource shares for "servername" are much lower than the virtual machines in the resource pool. With its current share settings, this virtual machine will be entitled to 13% of the CPU resources in the pool. Do you want to continue?

What does this mean exactly?

[pratjain]

This should be helpful

http://www.vmadmin.info/2011/04/cpu-resource-shares-bug.html

[willstej83]

This is driving me nuts. Maybe I am not understanding this feature of resource pools. If I create a resource pool for my SQL servers and set the pool to "high" shares this means that this resource pool will get resources from the cluster over any other resource pools set for "normal or low" correct?

Now within the Resource pool I have 3 SQL servers they all have different CPU counts and memory values. Now can I change the share values on each VM as needed? The way I understand it is that you don't want to max out the share percentage in a pool?

[Linjo]

Shares only come into play when the resources are depleted and ESX needs to prioritize between the workloads, the number of shares is irrelevant, its the percentage of the total shares that is important.

For example, you have 3 SQL servers, 1 with 1000 shares and 2 with 500. That means a total of 2000 shares.

If the resources are depleted the SQL with 1000 shares will get 50% of the available resources and the other 2 25% each.

// Linjo

[willstej83]

Got it. Now what if the sql server with 1000 shares/50% is not using all 50% and lets say one other sql server needs more than 25%? Is this where Expandable Reservation comes in? Is it smart to have all percentages = 100%? Should be leave some extra unused for VMs that need a bit more?

Is it ok to modify the vm resource settings when its in a resource pool? I cant see why not?

[Linjo]

Again, the share does only come into play when there is resource contention, when the workloads demands more capacity then whats available.