Technical data

______________________ Note _______________________
If you are using Fibre Channel storage, see Chapter 6.
Before you connect devices to a shared SCSI bus, you must:
• Plan your hardware configuration, determining which devices will be
connected to each shared SCSI bus, which devices will be connected
together, and which devices will be at the ends of each bus.
Planning is especially critical if you will install tape devices on the
shared SCSI bus. With the exception of the TZ885, TZ887, TL890,
TL891, and TL892, tape devices can only be installed at the end of a
shared SCSI bus. These tape devices are the only supported tape devices
that can be terminated externally.
• Place the devices as close together as possible and ensure that shared
SCSI buses will be within length limitations.
• Prepare the systems and storage shelves for the appropriate bus
connection, including installing SCSI controllers, UltraSCSI hubs,
trilink connectors, and SCSI signal converters.
After you install all necessary cluster hardware and connect the shared
SCSI buses, be sure that the systems can recognize and access all the shared
disks. (See Section 4.3.2.) You can then install the TruCluster Server
software as described in the
Cluster Installation manual.
4.1 Planning Your TruCluster Server Hardware
Configuration
Before you set up a TruCluster Server hardware configuration, you must
plan a configuration to meet your performance and availability needs. You
must determine the following components for your configuration:
• Number and type of member systems and the number of shared SCSI
buses
You can use two to eight member systems for TruCluster Server. A
greater number of member systems connected to shared SCSI buses
gives you better application performance and more availability. However,
all the systems compete for the same buses to service I/O requests, so a
greater number of systems decreases I/O performance.
Each member system must have a supported SCSI adapter for each
shared SCSI bus connection. There must be enough PCI slots for the
Memory Channel cluster interconnects and SCSI adapters. The number
of available PCI slots depends on the type of AlphaServer system.
4–2 TruCluster Server System Configuration Using UltraSCSI Hardware