Managing Serviceguard A.11.20, March 2013

Quorum Server as the cluster lock. In selecting a cluster lock configuration, be careful to anticipate
any potential need for additional cluster nodes.
For more information on lock disks, lock LUNs, and the Quorum Server, see “Choosing Cluster
Lock Disks” (page 178), “Setting Up a Lock LUN” (page 178), and “Setting Up and Running the
Quorum Server” (page 181).
Cluster Lock Disk and Re-formation Time
cmquerycl (1m) displays the failover time for the cluster in the Possible Cluster Lock
Devices section, for example:
Possible Cluster Lock Devices:
/dev/dsk/c0t1d4 30 seconds
Note: all lock disks have the same failover time
All disks in all volume groups which are accessible by all nodes in the cluster are potential cluster
lock devices, but because it takes a fixed amount of time to acquire the cluster lock, regardless of
the lock device, only the first potential lock device is displayed. You may need to choose a different
device because of power considerations; see “Power Supply Planning ” (page 102).
Planning for Expansion
Bear in mind that a cluster with more than 4 nodes cannot use a lock disk or lock LUN. Thus, if
you plan to add enough nodes to bring the total to more than 4, you should use a Quorum Server.
Using a Quorum Server
The operation of Quorum Server is described under “Use of the Quorum Server as the Cluster
Lock” (page 49). See also “Cluster Lock ” (page 47), “Specifying a Quorum Server” (page 194),
and the QS_HOST and QS_ADDR parameter descriptions under “Cluster Configuration Parameters
” (page 114).
IMPORTANT: If you plan to use a Quorum Server, make sure you read the HP Serviceguard
Quorum Server Version A.04.00 Release Notes before you proceed. You can find them at: http://
www.hp.com/go/hpux-serviceguard-docs under HP Serviceguard Quorum Server
Software . You should also consult the Quorum Server white papers at the same location.
A quorum server:
• Can be used with up to 150 clusters, not exceeding 300 nodes total.
• Can support a cluster with any supported number of nodes.
• Can communicate with the cluster on up to two subnets (a primary and an alternate) using
either IPv4 or IPv6 addresses.
Quorum Server Worksheet
You may find it useful to use a Quorum Server worksheet, as in the example that follows, to identify
a quorum server for use with one or more clusters. You may also want to enter quorum server host
and timing parameters on the Cluster Configuration Worksheet. Blank worksheets are in Blank
Planning Worksheets (page 375).
You can use the Quorum Server worksheet to record the following:
Quorum Server Host The host name (and alternate address, if any) for the quorum
server.
IP Address The IP address(es) by which the quorum server will be connected
to the cluster.
104 Planning and Documenting an HA Cluster