Managing Superdome Complexes: A Guide for HP-UX System Administrators

Planning Superdome Configurations
Rules and Guidelines for Configuring a Complex
Appendix A338
Guidelines for High Availability
• Make sure that more than one cell in each partition has an I/O
chassis containing core I/O (partitions containing only one cell, or
connected to only one I/O chassis, are not recommended).
The cells attached to chassis containing core I/O should be the
partition’s lowest-numbered cells. Each I/O chassis that contains core
I/O should also contain cards for a boot device and networking, placed
as described under “Rules” on page 336, but only one chassis with
core I/O also has to have a removable-media controller card (this
chassis should normally be the one attached to the lowest-numbered
cell).
This redundancy will allow you to reboot the partition and continue to
use it if any one cell connected to core I/O should fail in any respect
(e.g., a failure in the cell itself, the I/O chassis it's attached to, or the
core I/O card in the I/O chassis).
• As far as possible, keep all the I/O chassis for a single partition in a
single cabinet.
Add an expansion cabinet only when all the slots in all the I/O chassis
in the CPU cabinet(s) have been used up; and in a 64-way-capable
system, add a second expansion cabinet only when all the available
slots in the first expansion cabinet have been used up.
But see “Guidelines for Expandability” on page 340 for a possible
exception.
• If you are using an I/O expansion cabinet, make sure each partition
has at least one cell attached to core I/O inside the CPU cabinet.
• Put a core I/O card and a boot card in every I/O chassis.
• Within a partition, spread redundant cards across I/O chassis such
that if one I/O chassis fails, you still have sufficient connections to run
the system.
• Attach critical disk devices to cards in more than one I/O chassis, and
hence to more than one cell.
Some disk devices (such as a disk array with two SCSI controllers)
can be connected to more than one card. Use such devices for root and
boot disks, and also for disks containing mission-critical data. This
will allow you to get to the data on the disk even if the cell to which it