Fabric Services
LUN Masking & Mapping
LUN Masking
• LUN masking controls the
visibility of LUNs to hosts:
Host A
– The SAN administrator determines
which hosts are allowed to “see”
which LUNs A B
1GB Dx
– Prevents hosts from accessing SAN 2GB Dx
volumes that do not belong to them
RAID
1GB x D
• Usually implemented within the
A B
1GB Dx
Storage Subsystem
2GB x D
Host B
RAID
1GB x D
• 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