Managing Serviceguard Fifteenth Edition, reprinted May 2008

Planning and Documenting an HA Cluster
Hardware Planning
Chapter 4 139
NOTE When a boot/root disk is configured with a low-priority address on a
shared SCSI bus, a system panic can occur if there is a timeout on
accessing the boot/root device. This can happen in a cluster when many
nodes and many disks are configured on the same bus.
The correct approach is to assign SCSI addresses in such a way that the
interface cards on cluster nodes have the highest priority SCSI
addresses, followed by any boot/root disks that are on the shared bus,
followed by all other disks on the shared bus.
Disk I/O Information
Collect the following information for each disk connected to each disk
device adapter on the node:
Bus Type Indicate the type of bus. Supported busses are Fibre
Channel and SCSI.
Slot Number Indicate the slot number in which the interface card is
inserted in the backplane of the computer.
Address Enter the bus hardware path number, which will be
seen on the system later when you use ioscan to
display hardware.
Disk Device File
Enter the disk device file name. To display the name
use the ioscan -fnC disk command (for legacy DSFs)
or ioscan -fnNC disk (for agile addressing).
This information is used in creating the mirrored disk configuration
using Logical Volume Manager. In addition, it is useful to gather as much
information as possible about your disk configuration. You can obtain
information about available disks by using the following commands: