1. A method of allowing a virtual machine (VM), executing on a physical node, to access a storage area network (SAN), comprising: associating a unique identifier with said VM, wherein said unique identifier differs from other unique identifiers associated with other VMs executing on the physical node; and when dynamic unique identifier addressing is supported such that a host bus adapter (HBA) of the physical node is allowed to dynamically use different unique identifiers to access logical unit numbers (LUNs), instructing said physical node to use said unique identifier associated with said VM, rather than a unique identifier associated with said HBA of the physical node, when communicating with a logical unit number (LUN) associated with said VM and stored in said SAN in order to perform an input/output operation for said VM, wherein said LUN is allocated for access to said VM based on the use of the unique identifier and said LUN is not accessible by other VMs with different unique identifiers that are executing on the physical node.