Compaq AA-RHGWC-TE manual Two-Node Cluster with Two UltraSCSI DS-BA356 Storage Units

UNIX Version 5.0, 16 devices are supported on a SCSI bus. Therefore, multiple BA356 storage units can be used on the same SCSI bus to allow more devices on the same bus.

Figure 1–4 shows the configuration in Figure 1–3 with a second UltraSCSI BA356 storage unit that provides an additional seven disks for highly available applications.

Figure 1–4: Two-Node Cluster with Two UltraSCSI DS-BA356 Storage Units

				Network
		Member					Member
		System		Memory			System
		1		Channel	2
				Interface
		Memory Channel				Memory Channel
	Host Bus Adapter (ID 6)					Host Bus Adapter (ID 7)
			UltraSCSI	Shared		UltraSCSI
Tru64			BA356			BA356
				SCSI
UNIX				Bus
Disk
			Clusterwide	ID 0				ID 8
			/, /usr, /var
			Member 1					ID 9
			Boot Disk	ID 1
			Member 2	ID 2				ID 10
			Boot Disk
			Quorum	ID 3		Data		ID 11
			Disk			Disks
Data			ID 4	ID 4				ID 12
disks			ID 5
Do not use for				ID 5				ID 13
data disk. May								ID 14 or
be used for				ID 6				redundant
redundant power								power
supply.			PWR			PWR		supply

ZK-1590U-AI

This configuration, while providing more storage, has a single SCSI bus that presents a single point of failure. Providing a second SCSI bus would allow the use of the Logical Storage Manager (LSM) to mirror the /usr and /var

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