Virtual machine storage provisioning historically has imposed operational challenges. Monitoring datastore capacity and I/O load has proven to be very difficult and as a result is often neglected. During the provisioning process for virtual machines, virtual disk datastores are often randomly selected, leading to hot spots and over- or underutilized data-stores. Storage DRS is a new feature introduced in VMware vSphere 5.0 that provides smart virtual machine placement and load balancing mechanisms based on I/O and space capacity.
It will help decrease operational effort associated with the provisioning of virtual machines and monitoring of the storage environment. This document presents an overview of best practices for customers considering the implementation of VMware vSphere Storage DRS in combination with advanced storage device features or other VMware products.
http://www.vmware.com/files/pdf/techpaper/vsphere-storage-drs-interoperability.pdf
http://www.vmware.com/files/pdf/techpaper/vsphere-storage-drs-interoperability.pdf