VMware and IP Storage From EMC
Deploying shared storage is a big step toward gaining maximum value from VMware's higher level functionality. All ESX servers in the cluster need to have access to all of the storage for the cluster so that VMotion, HA, DRS, and DPM can execute. Shared storage is a requirement. Consolidating applications helps to achieve maximum resource utilization of the hardware investment. Consolidating applications results in consolidated I/O workloads, so each ESX server is driving significantly more load on the storage infrastructure than the non-virtualized ones it replaced. Additionally, VMware functions including VMotion and DRS can move I/O loads dynamically without involvement from the storage administrator.