Installation guide

Appendix A. Supplementary Hardware Information 143
Figure A-5. Dual-controller RAID Array Connected to Single-initiator SCSI Buses
A.3.1. SCSI Configuration Requirements
SCSI devices must adhere to a number of configuration requirements to operate correctly.
Failure to adhere to these requirements adversely affects cluster operation and resource
availability.
The following is an overview of SCSI configuration requirements:
• Buses must be terminated at each end. Refer to Section A.3.2 SCSI Bus Termination for
more information.
• Buses must not extend beyond the maximum length restriction for the bus
type. Internal cabling must be included in the length of the SCSI bus. Refer to
Section A.3.3 SCSI Bus Length for more information.
• All devices (host bus adapters and disks) on a bus must have unique SCSI identification
numbers. Refer to Section A.3.4 SCSI Identification Numbers for more information.
• The Linux device name for each shared SCSI device must be the same on each cluster
system. For example, a device named /dev/sdc on one cluster system must be named
/dev/sdc on the other cluster system. One way to ensure that devices are named the
same is by using identical hardware for both cluster systems.
Use the system’s configuration utility to set SCSI identification numbers and enable host
bus adapter termination. When the system boots, a message is displayed describing how
to start the utility. For example, the utility prompts the user to press [Ctrl]-[A], and follow
the prompts to perform a particular task. To set storage enclosure and RAID controller ter-
mination, refer to the vendor documentation. Refer to Section A.3.2 SCSI Bus Termination
and Section A.3.4 SCSI Identification Numbers for more information.