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Chapter 7 Cluster Installation and Configuration
97
SCSI Drive Installations
This information is provided as a generic instruction set for SCSI drive installations. If the
SCSI hard disk vendor’s instructions conflict with the instructions in this section, always
use the instructions supplied by the vendor.
The SCSI bus listed in the hardware requirements must be configured prior to installation
of Cluster Services. This includes:
• Configuring the SCSI devices.
• Configuring the SCSI controllers and hard disks to work properly on a shared SCSI
bus.
• Properly terminating the bus. The shared SCSI bus must have a terminator at each
end of the bus. It is possible to have multiple shared SCSI buses between the nodes
of a cluster.
In addition to the information on the next page, refer to the documentation from the SCSI
device manufacturer or the SCSI specifications, which can be ordered from the American
National Standards Institute (ANSI). The ANSI web site contains a catalog that you can
search for the SCSI specifications.
Configuring the SCSI Devices
Each device on the shared SCSI bus must have a unique SCSI ID. Since most SCSI
controllers default to SCSI ID 7, part of configuring the shared SCSI bus will be to
change the SCSI ID on one controller to a different SCSI ID, such as SCSI ID 6. If there
is more than one disk that will be on the shared SCSI bus, each disk must also have a
unique SCSI ID.
Some SCSI controllers reset the SCSI bus when they initialize at boot time. If this occurs,
the bus reset can interrupt any data transfers between the other node and disks on the
shared SCSI bus. Therefore, SCSI bus resets should be disabled if possible.
Terminating the Shared SCSI Bus
You can connect Y cables to devices if the device is at the end of the SCSI bus. You can
then attach a terminator to one branch of the Y cable to terminate the SCSI bus. This
method of termination requires either disabling or removing any internal terminators the
device has.
Trilink connectors can be connected to certain devices. If the device is at the end of the
bus, you can use a trilink connector to terminate the bus. This method of termination
requires either disabling or removing any internal terminators the device contains.
Y cables and trilink connectors are the recommended termination methods, as they
provide termination even when one node is not online.
Note:
Any devices that are not at the end of the shared bus must have their internal termination
disabled.