IBM 3531 manual Clustering support, General, Disk drive storage

General			•	User interface:		ESM boards
•	Modular components:			—	Built-in power, activity,	•	Technology and interfaces:
	—	High-capacity disk			and fault indicators		— SCSI: Ultra160
				—	Identification labeling
		drives					— SCSI bus interface: Two
	—	Environmental services			on customer replaceable
							68-pin, Very High
					units (CRUs) rear
		monitor (ESM) boards					Density Connector
					indicator lights,
	—	Power supplies with					Interface (VHDCI)
					switches, and connectors
							connectors for SCSI bus
		built-in fans		—	Easy-to-replace drives,
							cables
•	Technology:
					power supplies, ESM
	—	Supports disk array			boards, and fans
		technology	Disk drive storage
	—	Supports clustering
			•	Current capabilities:
	—	SCSI (Ultra160) host
				—	Maximum drives per
		interface
					expansion unit: 14
	—	Redundant data storage,
				— Drives per SCSI bus: 7
		power and cooling
		system, and ESM boards		—	SCSI buses per unit: 2
	— Hot-swap technology for			— SCSI buses can be
		drives, power supplies			configured as one
		with built-in fans, and			continuous SCSI bus.
		ESM boards

Clustering support

Clustering is a feature of the expansion unit. Clustering is a means of sharing SCSI buses and disk drives among SCSI controllers to provide redundancy of SCSI controllers and servers. This redundancy is important if a hardware component fails. If a hardware component fails after clustering has been set up, another server will take ownership of the disk drives or SCSI bus.

The IBM Netfinity EXP300 supports twin-tailed clustering. With twin-tailed

clustering, you can connect two IBM ServeRAID® controllers to an EXP300 expansion unit. In the twin-tailed clustering environment, you can use dual-host controllers cabled separately to the EXP300 expansion unit; however, only a single logical bus of 13 drives is supported. Each SCSI device on a SCSI bus must have a unique ID. To prevent conflicts in a twin-tailed configuration, do not install a drive in the bay that uses SCSI ID 6 because your secondary SCSI ServeRAID controller is set to 6.

Service tip: If you use IBM ServeRAID controllers in a cluster configuration, the termination power LED on the back of the expansion unit is useful. The ServeRAID controller provides the signal for termination power. If the termination power LED is not lit, it indicates that a particular EXP300 expansion unit is not attached to a controller that is turned on. Make a note of which EXP300 expansion unit is attached to which server before the hardware is serviced.

Clustering requires additional hardware and specialized software. For more information, visit the IBM Netfinity Cluster Solutions Web site at:

http://www.ibm.com/pc/us/netfinity/clustering

2IBM Netfinity EXP300 - Type 3531 Hardware Maintenance Manual