IBM DS3200 Storage Subsystem Redundant drive channel pair, Example of a redundant drive path

System Storage DS3000 Support CD. Incorrect drive migration might cause loss of configuration and other storage subsystem problems. Contact your IBM technical-support representative for additional information.

Redundant drive channel pair

Each RAID controller on the DS3200 has a drive expansion channel that contains an x4 SAS port. The storage expansion enclosures that are connected to this connector form a drive channel. The maximum number of hard disk drives that can be installed in one drive channel is 48. In a dual-controller DS3200, one drive channel from each controller combines to form a redundant drive-channel pair.

Figure 18 shows an example of a redundant drive-channel pair. If any component of the drive channel fails, the RAID controllers can still access the storage expansion enclosures in the redundant drive-channel pair.

Note: In storage expansion enclosures that are connected to a dual-controller storage subsystem, you must install the optional second ESM to support dual redundant drive paths.

Server
	To SAS HBA controller 1		To SAS HBA controller 2
DS3200		RAID controller A		RAID controller B

	SAS cable	To DS3200 RAID
EXP3000
		controller A

	SAS cable
EXP3000	SAS cable

SAS cable

EXP3000 SAS cable

SAS cable

To DS3200 RAID controller B

Figure 18. Example of a redundant drive path

Chapter 3. Cabling the storage subsystem 27