• LUN masking controls the visibility of LUNs to hosts:
– The SAN administrator determines which hosts are allowed to “see” which LUNs
– Prevents hosts from accessing volumes that do not belong to them
• Usually implemented within the Storage Subsystem
• Particularly important when multiple HBAs are configured in one host:
– Prevents the host from seeing multiple copies of each LUN
LUN masking:
LUN masking refers to the process of “hiding” logical units from specific HBA ports.
LUN masking helps to prevent hosts from “seizing” storage assets and making them unavailable to other hosts, and prevents two devices from attempting to write to the same storage location. LUN masking is also used when multiple HBAs are configured in one host. Each logical unit must be visible to only one HBA to prevent the host from seeing two copies of each logical unit - unless a multipathing driver is installed on the host