Managing Serviceguard Extension for SAP on Integrity Linux, December 2005

Step by Step Installation of SGeSAP on Integrity Linux for SAP WAS Central Instances
Cluster Configuration
Chapter 266
OS650 Optional Step:
It is possible to failover both packages of the two package concept to the
same node. If both packages try to come up on a single node after a
failover at the same time, it is likely that the Central Instance package
wants to start up the Central Instance before the database is fully
recovered. Without special precautions, this would lead to a failure
because SAP cannot connect to the database
To deal with this situation, there is a loop implemented that polls the
database in increasing intervals of time. The startup of the CI package is
delayed until the database is reached. After the first poll, the script will
wait 5 seconds before initiating the next polling attempt. The polling
intervall is doubled after each attempt with an upper limit of 30 seconds.
Polling continues until the resource becomes available or up to a
maximum of DELAY_INTERVALS polling attempts.
DELAY_INTERVALS also influences the duration of some other
waitstates and can be used to finetune the duration of a package startup
for a system that might be extremely busy or a system for that
recovering is exceptionally fast. Usually the parameter needs no
adoption unless a timing issue has been identified.
OS660 Optional Step:
Control the handling of resources. Prior to any instance startup,
SGeSAP/LX IPF tries to free up unused or unimportant resources to
make the startup more likely to succeed.
The potential values for CLEANUP_POLICY are lazy, normal and strict.
The value “lazy” deactivates any cleanup. The value “normal” cleans up
unused shared memory of the SAP System to which the package belongs.
The value “strict” cleans up all shared memory of SAP and database.
NOTE Do not use the strict policy unless it is critical that you do. Be sure
that the strict option can crash running instances of different SAP
systems on the backup host!
Use this value only if you have a productive system that is much more
important than any other SAP system you have. In this case a
switchover of the productive system is more robust, but additional SAP
components will crash.