2 December 1999
PFC 500/E Instruction Manual
71
The terms and definitions listed below are related to the storage system described in
this manual. Understanding them will aid your understanding of the storage system.
ALPA (arbitrated loop physical address) — An 8-bit address that uniquely
identifies a device on an FC loop.
bind — In the context of a disk-array storage system, the procedure by which you
hardware-format one or more disk modules into one LUN (logical unit) - usually as
one of several types of RAID group.
BTU (British Thermal Unit) — A standard measure of a device’s heat output.
cache — See storage-system caching.
CA (chassis address) — A number, selectable on a PFC 500/E front panel, set to 0
on an PFC500, that helps establish a unique address for each disk module on an
FC-AL loop. You must set the CA on each RAID Expansion Chassis (PFC 500E).
Since the PFC500 CA is 0, you might set the first PFC500E CA to 1 and the second
to 2.
CRU (customer-replaceable unit) — A hardware component, like a disk module,
that anyone can install or replace.
disk-drive module — Another name for disk module.
disk unit — A short name for physical disk unit.
disk module — A self-contained disk drive that slides into one of the slots in the
front of the storage system. It consists of the carrier assembly, which holds the disk
drive and the regulator board. Also called disk-drive module.
DIMM (dual in-line memory module) — A type of memory module used in RC
memory for write caching or RAID 3 memory.
EMI (electromagnetic interference) — Electronic radiation emitted by an electrical
device. The levels of EMI are strictly controlled for data processing equipment. The
EMI standards are explained after the Notice page near the beginning of the manual.
ESD (electrostatic discharge) — The discharge of an accumulated electrical charge
(static). This can severely damage delicate electronic circuits and you should take
steps to prevent this, as explained in the Chapter 3, “Servicing and upgrading a
PFC500/E”.
FC-AL (Fibre Channel arbitrated loop) — An arrangement of Fibre Channel
stations such that messages pass from one to the next in a ring.
FC-AL address ID — A number that identifies a device as a node on a fibre channel
loop. You select the FC-AL address ID for an SP using switches on the RC. The
Glossary