IBM RS/6000 manual Pdisks, Hdisks, Disk, Identification, Rules for SSA Loops

Pdisks, Hdisks, and

Disk

Drive

Module

Identification

The physical

disk

drives (pdisks)in an SSA

subsystem can

be configured as

l

units (LUNs). A LUN is also

knownhdias,k and can consist of one or more

physical

disk

drives. An

hdisk

in

an

SSA subsystem

might therefore

co

or

more

pdisks.

The

configuration

software

also allocates an identification (hdisk an

to each disk drive module

during the configuration of the SSA link.

modules

do

not

have

fixed

physical

addresses.

The configuration software first recognizes the disk drive module b

readable serial number that is				written	on	the	disk. Then,		it	assign
that is related to the position of the disk							drive-module in the SS
uration,	the disk	drive	module	always has		the	same	identification.
to any	position on	the	SSA link,	but can	always		be	found	by	the so

Service actions are always related to physical disk drives. For thi that occur on SSA disk drives are always logged against the physic (pdisk).

The	numeric		identifier	of pdisks, hdisks, and disk	drive	module	slot
unit	are not related			to each other. For example,	pdisk1	is not	nec
slot	1	of	the 6-pack.
The disk drive module serial number, on the label					on the	front	of
displayed by the service aids. It is the last					eight	digits	of
unique		ID,	which is	stored on the drive's electronics card.

Rules for SSA Loops

The following are the rules for connecting SSA loops:

ŸThe SSA loop must be connected to the internal pair of connectors adapter.

Ÿ	Only one	pair	of adapter	connectors can be connected to a par
Ÿ	A maximum	of	18 disk drive	modules can be connected in a partic

ŸA maximum of three dummy disk drive modules can be connected nex other in a particular SSA loop.

Chapter 7. Using the Service7-27Aids