HP-UX HB v13.00 Ch-15 - Serviceguard

HP-UX Handbook – Rev 13.00 Page 91 (of 108)
Chapter 15 Serviceguard
October 29, 2013
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Backing Up Cluster Lock Disk Information
After you configure the cluster and create the cluster lock volume group and physical volume,
you should create a backup of the volume group configuration data on each lock volume group.
# vgcfgbackup <vg_lock>
Replacing a failed Cluster Lock Disk
See ”Useful Procedures and Commands”, Reconfiguring a Cluster
Use of the Quorum Server as the Cluster Lock
A quorum server can be used in clusters of any size or for multiple clusters.
The quorum server process runs on a machine outside of the cluster for which it is providing
quorum services. The quorum server listens to connection requests from the Serviceguard nodes
on a known port. The server maintains a special area in memory for each cluster, and when a
node obtains the cluster lock, this area is marked so that other nodes will recognize the lock as
“taken.” If communications are lost between two equal-sized groups of nodes, the group that
obtains the lock from the Quorum Server will take over the cluster and the other nodes will
perform a TOC. Without a cluster lock, a failure of either group of nodes will cause the other
group, and therefore the cluster, to halt. Note also that if the quorum server is not available
during an attempt to access it, the cluster will halt. The operation of the quorum server is shown
in the Figure below.
Quorum Server Operation
Setting up the Quorum Server
The quorum server software, must be installed on a system other than the nodes on which your
cluster will be running. The actual Quorum Server Version is 3.0
NOTE It is recommended that this node is in the same subnet as the clusters for which it is
providing services. This will help prevent any network delays which could affect quorum server
nodeA
nodeB