Managing Serviceguard Extension for SAP Version B.05.10, December 2012

Optional Step: OS720
If several packages start on a single node after a failover, it is likely that some packages start up
faster than others on which they might depend .
To allow synchronization in this case, there is a loop implemented that polls the missing resources
regularly.
After the first poll, the script will wait 5 seconds before initiating the next polling attempt. The
polling interval 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.
Optional Step OS730
If several packages start on a single node after a failover, it is likely that some packages start up
faster than others on which they might depend .
To allow synchronization in this case, there is a loop implemented that polls the missing resources
regularly.
Control the handling of resources.
Prior to any instance startup, the SGeSAP tries to free up unused or unimportant resources to make
the startup more likely to succeed. A database package only frees up database related resources,
a Central Instance package only removes IPCs belonging to SAP administrators.
The following list summarizes how the behavior of SGeSAP is affected by changing the
CLEANUP_POLICY parameter:
• Lazy—no action, no cleanup of resources
• Normal—removes unused resources belonging to the own system
• Strict—uses HP-UX commands to free up all semaphores and shared memory segments that
belong to any SAP Instance of any SAP system on the host if the Instance is to be started soon.
It uses HP-UX to free up all semaphores and shared memory segments that belong to any
database if the SAP database is to be started soon.
NOTE: Do not use the strict policy unless it is critical that you do. Be aware 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 systems will crash.
You can also use strict policy, if your SAP system is the only one running at the site and you are
low on memory. Strict policy frees up more of its own shared memory segments than the normal
policy does.
For the cleanup of resources cleanipc is used—an SAP tool to free up the IPC resources of
specific SAP Instances. It is used to free up resources of an Instance that is to be started soon on
HP-UX. This prevents shared memory issues caused by the remains of a prior crash of the Instance.
Accordingly, an obsolete ORACLE SGA is also removed if a database crash occurred.
Optional Parameters and Customizable Functions
In /etc/cmcluster/<SID> there is a file called customer.functions that provides a couple
of predefined function hooks. They allow the specification of individual startup or runtime steps at
certain phases of the package script execution. Therefore, it is not necessary and also not allowed
to change the sap.functions.
In the following, there is a summary of the function hooks in chronological order:
100 Step-by-Step Cluster Conversion