multiple BA356 storage units can be usedon the same SCSI bus to allowmore devices on the same bus.Figure 1–4 shows the configuration in Figure 1–3 with a second UltraSCSIBA356 storage unit that provides an additional seven disks for highlyavailable applications.Figure 1–4: Two-Node Cluster with TwoUltraSCSI DS-BA356Storage Units
ID 8
ID 9
ID 10
ID 11
ID 12
ID 13
PWR
ID 5
PWR
Shared
SCSI
Bus
Clusterwide
/, /usr, /var
Member 1
Boot Disk
Member 2
Boot Disk
Quorum
Disk
UltraSCSI
BA356
ID 4
ID 14 or
redundant
power
supply
Host Bus Adapter (ID 7)
Network
Memory
Channel
Interface
Memory Channel
Host Bus Adapter (ID 6)
Memory Channel
Member
System
2
Member
System
1
Tru64
UNIX
Disk
ID 5
ID 4
ID 6
ID 3
ID 2
ID 1
ID 0
Data
disks
Do not use for
data disk. May
be used for
redundant power
supply.
Data
Disks
UltraSCSI
BA356
ZK-1590U-AI
This configuration, while providing more storage, has a single SCSI bus thatpresents a single point of failure. Providing a second SCSI bus would allowthe use of the Logical Storage Manager (LSM) to mirror the /usr and /varfile systems and the data disksacross SCSI buses, removing the single SCSIbus as a single point of failure for these file systems.

Introduction 1–11