Managing HP Serviceguard for Linux Ninth Edition, April 2009

quorum server, or quorum server cluster, make sure each quorum server node has a
power source separate from that of every cluster it serves. If you use software mirroring,
make sure power supplies are not shared among different physical volume groups;
this allows you to set up mirroring between physical disks that are not only on different
I/O buses, but also connected to different power supplies.
To prevent confusion, 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, power circuit, and cabinet power limits as well as SPU power
limits.
Power Supply Configuration Worksheet
The Power Supply Planning worksheet (page 311) will help you organize and record
your specific power supply configuration. Make as many copies as you need.
Cluster Lock Planning
The purpose of the cluster lock is to ensure that only one new cluster is formed in the
event that exactly half of the previously clustered nodes try to form a new cluster. It is
critical that only one new cluster is formed and that it alone has access to the disks
specified in its packages. You can specify a lock LUN or a quorum server as the cluster
lock. For more information about the cluster lock, see“Cluster Lock” (page 45).
NOTE: You cannot use more than one type of lock in the same cluster.
Cluster Lock Requirements
A one-node cluster does not require a lock. Two-node clusters require the use of a
cluster lock, and a lock is recommended for larger clusters as well. Clusters larger than
four nodes can use only a quorum server as the cluster lock.
For information on configuring lock LUNs and the Quorum Server, see “Setting up a
Lock LUN” (page 157), “Specifying a Lock LUN” (page 172), and the HP Serviceguard
Quorum Server Version A.04.00 Release Notes at http://www.docs.hp.com -> High
Availability -> Quorum Server.
98 Planning and Documenting an HA Cluster