Technical data

• Using a redundant array of independent disks (RAID) array controller in
transparent failover mode allows the use of hardware RAID to mirror the
disks. However, without a second SCSI bus, second Memory Channel,
and redundant networks, this configuration is still not an NSPOF cluster
(Section 1.5.4).
• By using an HSZ70, HSZ80, or HSG80 with multiple-bus failover
enabled, you can use two shared SCSI buses to access the storage.
Hardware RAID is used to mirror the root (
/), /usr, and /var file
systems, and the member system boot disks, data disks, and quorum
disk (if used). A second Memory Channel, redundant networks, and
redundant power must also be installed to achieve an NSPOF cluster
(Section 1.5.5).
______________________ Note _______________________
The figures in this section are generic drawings and do not show
shared SCSI bus termination, cable names, and so forth.
1.5.1 Two-Node Clusters Using an UltraSCSI BA356 Storage Shelf
and Minimum Disk Configurations
This section takes the generic illustrations of our cluster example one step
further by depicting the required storage in storage shelves. The storage
shelves can be BA350, BA356 (non-UltraSCSI), or UltraSCSI BA356s. The
BA350 is the oldest model, and can only respond to SCSI IDs 0-6. The
non-Ultra BA356 can respond to SCSI IDs 0-6 or 8-14 (see Section 3.2). The
UltraSCSI BA356 also responds to SCSI IDs 0-6 or 8-14, but also can operate
at UltraSCSI speeds (see Section 3.2).
Figure 1–3 shows a TruCluster Server configuration using an UltraSCSI
BA356 storage unit. The DS-BA35X-DA personality module used in the
UltraSCSI BA356 storage unit is a differential-to-single-ended signal
converter, and therefore accepts differential inputs.
1–8 Introduction