IBM DS4700 manual Introduction

comprise the enclosure ID are referred to as x10 and x1 digits. The enclosure ID provides a unique identifier for each enclosure in the storage subsystem. The storage management software automatically sets the enclosure ID number. You can only change the enclosure ID setting through the DS4000 storage management software. There are no switches on the DS4700 Express chassis to manually set the enclosure ID. Both controller enclosure ID numbers will be identical under normal operating conditions. The enclosure ID is set to a value of 85 from the factory.

Storage expansion enclosures in a DS4000 storage subsystem must also have unique enclosure IDs. In addition to having unique enclosure IDs for each storage expansion enclosure (including the DS4000 storage subsystems with drives installed) in the DS4000 storage subsystem configuration, ensure 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 (including the DS4000 storage subsystem with drives installed) in a redundant drive channel/loop pair, then drive loop errors might be randomly posted in the DS4000 subsystem Major Event Log (MEL) when you intermix different types of storage expansion enclosures in a redundant drive loop pair (such as an EXP100 with an EXP810). For example, with four enclosures attached to a DS4500 in a redundant drive loop pair, the correct enclosure ID settings should be 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 DS4000 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 if you have storage expansion enclosures with mechanical switches such as EXP710s in the DS4000 configuration. This will prevent unnecessary downtime when you add enclosures of different types (especially EXP810s) to the existing enclosures in the redundant drive channel/loop pair. Storage expansion enclosures and DS4000 storage subsystems with mechanical enclosure ID switches require that you power cycle the configurations to activate the new enclosure ID settings. The EXP810 storage expansion enclosures do not required you to power cycle the DS4000 configuration to activate new enclosure ID settings.

Figure 2 on page 10 shows the controllers for DS4700 Express model 70. Figure 3 on page 10 shows the controllers for DS4700 Express model 72.

Chapter 1. Introduction 9