Checking on some vmware sites I see that DRS is more for monitoring the resources of your physical nodes in vmware and moving vm’s between those nodes when needed.
For example if you have 3 physical nodes running and each is only using 15%-20% of it’s resources, if you had DRS monitoring these in a cluster it would move the vm’s to either just 2 or even only 1 of the nodes and then power down the unused nodes to save power. when more resources are need it would power the unused nodes back on and move some of the vm’s to it so it can use more resources.
HA (High Availibility) is what is used in vmware to restart a vm on another node if the node it was running on had a hardware failure.
now from what I have seen if the storage is internal to the node then if the hardware failed then it would be impossible to move the vm to another node since the actual physical hard drives it was on is down. to do HA you would need to be using shared storage on a SAN. We are currently using an HP MSA2012 iSCSI SAN now and it works great.