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

CAUTION: This command may remove the file /var/log/qs/qs.log. If this
is your log file, you may want to save it before running this command.
3. Install the version of Quorum Server A.04.00 appropriate to your distribution and
hardware. For example:
rpm -ihv qs-A.04.00.00-0.sles10.i386.rpm
4. Uncomment the entry you commented out in /etc/inittab.
5. Re-start the Quorum Server:
/sbin/init q
Configuring Serviceguard to Use the Quorum Server
About the QS Polling Interval and Timeout Extension
Serviceguard probes the Quorum Server at intervals determined by the
QS_POLLING_INTERVAL parameter in the cluster configuration file. The default value
for QS_POLLING_INTERVAL is 5 minutes and the minimum value is 10 seconds.
If the quorum server process goes down while its node is still up, the Serviceguard
cluster nodes can detect the halt in the quorum server process. Serviceguard will try
to re-connect to the quorum server every 10 seconds until the quorum server is back
up and the connection is successful. If the quorum server is needed as a tie-breaker
during this downtime, the cluster will halt.
However, Serviceguard cannot immediately detect the loss of connection to the process
if the quorum server’s node goes down. Serviceguard will continue to poll at the
configured interval, and will not discover that the quorum server connection is down
until the next polling is done. If a cluster reformation starts before the next polling has
occurred, Serviceguard assumes the Quorum Server is down. Because it requires the
Quorum Server as a tie-breaker, it will halt the cluster. (Even if the Quorum Server
comes back up before or during reformation, Serviceguard will not know that it has
until the next polling.)
The minimum value for the polling interval is 10 seconds. Reducing the
QS_POLLING_INTERVAL means Serviceguard will detect Quorum Server failures
sooner, but it will also increase the load on the Quorum Server. If you set a short interval,
you may have to reduce the number of clusters or nodes using the Quorum Server to
reduce the load. Test very low settings carefully to fine-tune all timing parameters, and
do the tests in an environment that imitates the actual production environment as
closely as possible.
You can use the optional QS_TIMEOUT_EXTENSION to increase the time interval (in
microseconds) after which the current connection (or attempt to connect) to the quorum
server is deemed to have failed; see “Network Recommendations” (page 12) and
“Setting Quorum Server Parameters in the Cluster Configuration File” (page 17).
16 HP Serviceguard Quorum Server Version A.04.00 Release Notes