HP Serviceguard Quorum Server Version A.04.00 Release Notes, revised August 2009

The version of the software you download is determined by the operating system you specify
on the download page.
Documentation for This Version
These release notes are shipped with Quorum Server Version A.04.00, and published under
Quorum Server at http://docs.hp.com -> High Availability.
Updated versions are published on that site as they become available.
See also the white paper Arbitration for Data Integrity in Serviceguard Clusters, under Quorum
Server at http://docs.hp.com -> High Availability.
Further Information
The most recent versions of user’s guides, release notes, and white papers about Serviceguard
and related topics are available at http://docs.hp.com -> High Availability.
Support information, including current information about patches and known problems, is
available from the Hewlett-Packard IT Resource Center:
http://itrc.hp.com (Americas and Asia Pacific) or http://europe.itrc.hp.com (Europe)
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.
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” (page 9), 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.”
In recent versions of Serviceguard, you can configure more than one connection between the
Quorum Server and each cluster node; see “Compatibility with Serviceguard Versions” (page 10)
and “Using Alternate Subnets” (page 13).
NOTE: The difference between Serviceguard A.11.19 and the earlier versions that support an
alternate-subnet connection is that in those earlier versions, the alternate connections are serialized:
if the first connection fails, the node will attempt to connect to the Quorum Server on the alternate
subnet. In A.11.19 the connections are created in parallel, improving availability: if one connection
fails, the other is still active.
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” (page 16).
You can also configure any two Serviceguard clusters to provide quorum services for each other;
for more information see the white paper, Cross-cluster Quorum Server Configurations at
docs.hp.com -> High Availability -> Quorum Server.
8 HP Serviceguard Quorum Server Version A.04.00 Release Notes