IBM TotalStorage DS4500 Cabling Manual page 6

Drive interface ports
DS4500 Storage Subsystems use only redundant drive-loop configurations. Each drive mini hub connects
to Controller A and Controller B and represents a single drive loop. The drive loops must be set up in
pairs to support redundant drive loop configurations (two data paths per storage expansion enclosure).
See Figure 4 for an illustration of the drive-side mini-hub interface ports.
Drive loop C and D for
redundant drive loop pair 2
Drive loop A and B for
redundant drive loop pair 1
2 Gb/s 2 Gb/s 2 Gb/s 2 Gb/s
1 Gb/s 1 Gb/s 1 Gb/s 1 Gb/s
! ! ! !
OUT OUT OUT OUT
IN IN IN IN
Use one port on each
mini hub to connect
a drive loop cable
Figure 4. Drive mini-hub ports
The maximum number of storage expansion enclosures that can be connected per pair of redundant drive
loops depends on the IBM DS4000 storage expansion enclosure models used. The following DS4000
storage expansion enclosure types are supported by the DS4500 Storage Subsystem:
v FAStT EXP500
v DS4000 EXP700
v DS4000 EXP710
v DS4000 EXP100
v DS4000 EXP810
If the drives are configured using only DS4000 EXP700, EXP710, EXP810, or EXP100 storage expansion
enclosures, the DS4500 Storage Subsystem supports a maximum of 224 hard drives.
If the drives are configured using only FAStT EXP500 storage expansion enclosures, the DS4500 Storage
Subsystem supports a maximum of 220 hard drives.
Important: Ensure that the single digit (x1) of the enclosure ID for every enclosure in a redundant drive
loop pair is unique. Refer to the IBM TotalStorage DS4500 Installation, User's, and Maintenance Guide for
more information on the storage expansion enclosure IDs settings.
To cable two DS4000 10- or 14- drive storage expansion enclosures (EXP500, EXP700, EXP710, or EXP100)
to the DS4500, see "Connecting to EXP500/EXP100/EXP700/EXP710 storage expansion enclosures" on
page 7. To cable two DS4000 16-drive storage expansion enclosures (EXP810) to the DS4500, see
"Connecting to EXP810 storage expansion enclosures" on page 8.
6
4 3 2 1
2 Gb/s 2 Gb/s 2 Gb/s 2 Gb/s
1 Gb/s 1 Gb/s 1 Gb/s 1 Gb/s
! ! ! !
Drive
OUT OUT OUT OUT
mini-hub
ports
IN IN IN IN
Leave one port unoccupied
for future upgrades
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