Managing HP Serviceguard A.12.00.00 for Linux, June 2014

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.

4.4.1 Power Supply Configuration Worksheet

The Power Supply Planning worksheet (page 299) will help you organize and record your specific

power supply configuration. Make as many copies as you need.

4.5 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 38).

NOTE:

• You cannot use more than one type of lock in the same cluster.

• An iSCSI storage device does not support configuring a lock LUN.

4.5.1 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 151), section “Specifying a Lock LUN” (page 166), and HP Serviceguard Quorum Server

Version A.04.00, or later Release Notes at http://www.hp.com/go/linux-serviceguard-docs (Select

HP Serviceguard Quorum Server Software).

4.5.2 Planning for Expansion

Bear in mind that a cluster with more than 4 nodes cannot use a lock LUN. So if you plan to add

enough nodes to bring the total to more than 4, you should use a quorum server.

4.5.3 Using a Quorum Server

The Quorum Server is described under “Use of the Quorum Server as a Cluster Lock” (page 39).