IBM DS3500, Installation, User'S, And Maintenance Manual

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Redundant drive channel pair
Each storage controller on the DS3500 has a drive expansion channel that contains an x4 SAS port. The
storage enclosures that are connected to this connector form a drive channel. The maximum number of
drives that can be installed in one drive channel is 96. In a dual-controller DS3500, one drive channel
from each controller combines to form a redundant drive-channel pair.
Figure 3-23 shows an example of a redundant drive-channel pair. If any component of the drive channel
fails, the controllers can still access the storage enclosures in the redundant drive-channel pair.
Note: In storage enclosures that are connected to a dual-controller storage subsystem, you must install
the optional second ESM to support dual redundant drive paths.
Overview of steps to connect storage enclosures to a storage subsystem
To connect storage enclosures to the storage subsystem, complete the following steps:
1. Follow the instructions in the IBM System Storage DS3500 and EXP3500 Rack Installation and Quick Start
Guide for your storage enclosure and the rack installation instructions to set up and mount the storage
enclosures.
2. Select a cabling topology applicable to the number of ESMs in the storage enclosures that you will
connect to the DS3500. “DS3500 storage subsystem drive cabling topologies” on page 3-21 describes
the recommended schemes for cabling storage enclosures with one ESM or two ESMs to the DS3500
and to each other (if you are connecting more than one storage enclosure).
3. Follow the cabling diagram for your chosen topology.
4. If required, set unique enclosure IDs for all storage enclosures that are cabled to the DS3500. See the
DS Storage Manager 10 Installation and Host Support Guide for information about setting the enclosure
ID.
Figure 3-23. Example of a redundant drive path
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System Storage DS3500 and EXP3500: Installation, User's, and Maintenance Guide