Managing Serviceguard Eighteenth Edition, September 2010

Replacing Failed I/O Cards
Depending on the system configuration, it is possible to replace failed disk I/O cards
while the system remains online. The process is described under “Replacing I/O Cards”
(page 406).
Sample SCSI Disk Configurations
Figure 2-2 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 2-2 Mirrored Disks Connected for High Availability
Figure 2-3 below shows a similar cluster with a disk array connected to each node on
two I/O channels. See “About Multipathing” (page 45).
Redundant Disk Storage 47