Back View; Controllers With Two Standard Fibre Channel Host Expansion Channels - IBM System Storage DS5020 Installation, User's, And Maintenance Manual

installed) in the DS5020 storage subsystem configuration, make sure that the single
digit (x1) of the enclosure ID for every storage expansion enclosure in a redundant
drive channel/loop pair is unique.
If you do not set the single-digit value of the enclosure IDs to be unique among
storage expansion enclosures in a redundant drive channel/loop pair, it will be
difficult to troubleshoot the source of errors in the drive channels. For example, with
four enclosures attached to a DS4500 in a redundant drive loop pair, the correct
enclosure ID settings are x1, x2, x3, and x4 (where x can be any digits that can be
set). Examples of incorrect settings would be 11, 21, 31, 41; or 12, 22, 32 62.
These examples are incorrect because the x1 digits are the same in all enclosure
IDs (either 1 or 2).
If the enclosure IDs in your subsystem configuration are not currently set to have
unique single-digit (x1) values for the enclosures in the same redundant drive
channel/loop pair, make the changes to the enclosure IDs in the next maintenance
schedule. The EXP520 and EXP810 storage expansion enclosures do not require
you to reset the power to the configuration to activate new enclosure ID settings.
Figure 2, Figure 3 on page 12, and Figure 4 on page 12 show the three different
DS5020 controller configurations that are available. Figure 2 shows the base
DS5020 storage subsystem, with two Fibre Channel host ports. For more
information about DS5020 controller options and other components, see the "Parts
listing" on page 166.
Serial Ethernet
port ports
Controller A
Enclosure ID
Figure 2. Back view; controllers with two standard Fibre Channel host expansion channels
Dual-ported
Fibre Channel
drive channel
host channels
Dual-ported
Fibre Channel
drive channel
host channels
Enclosure ID
Controller B
Ethernet Serial
ports port
Chapter 1. Introduction
11