Port identifiers (PIDs, also called Fabric Addresses) are used by the routing and zoning services in
Fibre Channel fabrics to identify ports in the network. All devices in a fabric must use the same PID
format. When you add new equipment to the SAN, you might need to change the PID format on
legacy equipment.

Many scenarios cause a device to receive a new PID; for example, unplugging the device from one
port and plugging it into a different port as part of fabric maintenance, or changing the domain ID
of a switch, which might be necessary when merging fabrics, or changing compatibility mode
settings.

Some device drivers use the PID to map logical disk drives to physical Fibre Channel counterparts.
Most drivers can either change PID mappings dynamically, also called dynamic PID binding, or use
the WWN of the Fibre Channel disk for mapping, also called WWN binding.

Some older device drivers behave as if a PID uniquely identifies a device; they use static PID
binding. These device drivers should be updated, if possible, to use WWN or dynamic PID binding
instead, because static PID binding creates problems in many routine maintenance scenarios.
Fortunately, very few device drivers still behave this way. Many current device drivers enable you to
select static PID binding as well as WWN binding. You should only select static binding if there is a
compelling reason, and only after you have evaluated the effect of doing so.