It is my experience that resource pools are nearly a four letter word in the virtualization world. Typically I see a look of fear or confusion when I bring up the topic. Even with some http://www.yellow-bricks.com/2010/02/24/custom-shares-on-a-resource-pools-scripted/out there that discuss this topic, a lack of education remains on how resource pools work, and what they do. In this post, I’ll give you my spin on some of the ideals behind a resource pool, show off a fancy infographic, and then discuss ways to properly balance resource pools by hand and with the help of PowerShell.
That’s a good question. You can’t even make a resource pool on a cluster unless you have DRS running. So, if your license level excludes this technology, you don’t have to worry about resource pools at all. If you are graced with the awesomeness of DRS, you may need a resource pool if you want to “weight” different types of workloads for two scenarios:
Now, this isn’t to say that a resource pool is the only way to accomplish these things – you can use per VM shares and reservations. But, these values sometimes reset when a VM vMotions to another host, and frankly it’s a bit of an administrative nightmare to manage resource settings on the VMs individually. I’ll give an exception to those using some sort of script, but it would require adding some creative solutions to identifying which VMs should be set to what resource values (folders, annotations, etc.).
See this: http://wahlnetwork.com/2012/02/01/understanding-resource-pools-in-vmware-vsphere/