HP Serviceguard Quorum Server Version A.03.00 Release Notes, December 2007

HP Serviceguard Quorum Server Version A.03.00 Release Notes
What Is the Quorum Server?
Chapter 1 9
What Is the Quorum Server?
Serviceguard cluster products are specialized facilities for protecting
mission-critical applications from a wide variety of hardware and
software failures. The HP Serviceguard Quorum Server provides
arbitration services for Serviceguard clusters when a cluster partition is
discovered: should equal-sized groups of nodes become separated from
each other, the Quorum Server allows one group to achieve quorum and
form the cluster, while the other group is denied quorum and cannot
start a cluster. See “How the Quorum Server Works” on page 9.
How the Quorum Server Works
The Quorum Server runs on an HP-UX or Linux system outside of the
cluster for which it is providing quorum services.
Within the restrictions specified under “System Requirements” on
page 10, a Quorum Server running on either a Linux or an HP-UX
system can serve a Serviceguard for Linux cluster, an HP-UX
Serviceguard cluster, or a combination of clusters of both types.
The Quorum Server uses TCP/IP, and listens to connection requests from
the Serviceguard nodes on port # 1238. The server maintains a special
area in memory for each cluster; when a node obtains the cluster lock,
this area is marked so that other nodes will recognize the lock as “taken.”
You can make the Quorum Server highly available by configuring it as a
Serviceguard package, so long as the package runs outside the cluster
the Quorum Server serves; see “Creating a Package for the Quorum
Server” on page 22.
You can also configure any two Serviceguard clusters to provide the
Quorum Server for each other; for more information see the white paper,
Cross-cluster Quorum Server Configurations at docs.hp.com -> High
Availability -> Quorum Server.
If the Quorum Server is not available or reachable, it will not adversely
affect any clusters using it, unless a cluster needs to reform and requires
the Quorum Server’s arbitration to do so.