Managing HP Serviceguard for Linux, Sixth Edition, August 2006

Planning and Documenting an HA Cluster
Power Supply Planning
Chapter 496
Power Supply Planning
There are two sources of power for your cluster which you will have to
consider in your design: line power and uninterruptible power supplies
(UPS). Loss of a power circuit should not bring down the cluster. No more
than half of the nodes should be on a single power source. If a power
source supplies exactly half of the nodes, it must not also supply the
cluster lock disk or quorum server or the cluster will not be able to
reform after a failure. See the section on cluster locks in “Cluster
Configuration Planning” for more information.
To provide a high degree of availability in the event of power failure, use
a separate UPS at least for each node's SPU and for the quorum server
system, and ensure that disks in separate storage units are connected to
different power supplies. This last rule enables disk mirroring to take
place between physical disks that are connected to different power
supplies as well as being on different I/O buses.
To prevent confusion, it is suggested that you label each hardware unit
and power supply unit clearly with a different unit number. Indicate on
the Power Supply Worksheet the specific hardware units you are using
and the power supply to which they will be connected. Enter the
following label information on the worksheet:
Host Name Enter the host name for each SPU.
Disk Unit Enter the disk drive unit number for each disk.
Tape Unit Enter the tape unit number for each backup device.
Other Unit Enter the number of any other unit.
Power Supply Enter the power supply unit number of the UPS to
which the host or other device is connected.
Be sure to follow UPS and cabinet power limits as well as SPU power
limits.
Power Supply Configuration Worksheet
The Power Supply Planning worksheet on page 327 will help you
organize and record your specific power supply configuration. Make as
many copies as you need. Fill out the worksheet and keep it for future
reference.