HP Serviceguard manual Cluster Lock Disk and Re-formation Time, Using a Quorum Server

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 173), “Setting Up a Lock LUN” (page 174), and “Setting Up and Running the Quorum Server” (page 177).

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 97).

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 48). See also “Cluster Lock ” (page 46), “Specifying a Quorum Server” (page 190), and the QS_HOST and QS_ADDR parameter descriptions under “Cluster Configuration Parameters ” (page 109).

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 369).

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.

Cluster Lock Planning 99