HP Serviceguard A.11.20- Managing Serviceguard Twentieth Edition, August 2011

Sample SCSI Disk Configurations
Figure 5 shows a two node cluster. Each node has one root disk which is mirrored and one package
for which it is the primary node. Resources have been allocated to each node so that each node
may adopt the package from the other node. Each package has one disk volume group assigned
to it and the logical volumes in that volume group are mirrored. Please note that Package A’s disk
and the mirror of Package B’s disk are on one interface while Package B’s disk and the mirror of
Package A’s disk are on a separate bus. This arrangement eliminates single points of failure and
makes either the disk or its mirror available in the event one of the buses fails.
Figure 5 Mirrored Disks Connected for High Availability
Figure 6 below shows a similar cluster with a disk array connected to each node on two I/O
channels. See “About Multipathing” (page 33).
Redundant Disk Storage 35