Managing Serviceguard Extension for SAP Version A.06.00 for Linux, December 2012

system administrators, that is, sidadm users that are logged in to the Linux operating system and
it includes remote SAP basis administration access via the SAP Management Console (SAP MC)
or SAP’s plugin for Microsoft Management Console (SAP MMC).
The SAP Netweaver 7.x startup framework is made up of a host control agent (hostctrl) software
process that runs on each node of the cluster and a sapstart service agent (sapstartsrv) software
per SAP instance. SGeSAP does not interfere with the host control agents, but interoperates with
the sapstart service agents during instance start, stop and monitoring operations.
SGeSAP cannot tolerate the administration usage of SAP 4.x and 6.x startsap and stopsap scripts.
They must be avoided. SGeSAP can use these scripts internally for startup and shutdown in case
the startup framework is not available, but its monitors would not be able to judge whether an
instance is down because of a failure or because of a stopsap operation. SGeSAP triggers an
instance restart or an instance failover operation in reaction to a stopsap call.
The startsap/stopsap scripts are not recommended by SAP with Netweaver 7.x and must not be
used anymore. It is recommended to configure startup framework agents for older SAP releases,
too.
NOTE: startsap and stopsap operations must not be used in clusters that have SAP software
monitors configured. sapcontrol operations can be used instead. For more information on how
to use sapcontrol with old SAP releases, see SAP note 995116.
Without a cluster, each sapstart service agent is statically registered in the SAP configuration of
the host on which its SAP instance was installed. In a cluster, such registrations become dynamic.
The cluster package start operations perform registration of the required agents and the cluster
package shutdown operations include deregistration routines. After cluster package start, all
required startup agents are registered and running. After cluster package halt, these startup agents
are halted and not registered. As a consequence, the attempt to start a SAP startup agent after
bringing down the instance package that it belongs to must fail, because the agent is not registered.
NOTE:
• sapcontrol –nr … –function StartService <SID> operations are usually not
required in SGeSAP environments. They fail if the package of the instance is down. A clustered
SAP instance might be accompanied with one or more SGeSAP service monitors that regularly
check whether the instance is up and running and whether it is responsive to service requests.
For this activity, the sapstart service agents are utilized. For the monitoring to operate it is thus
mandatory that the sapstart services remain running.
• sapcontrol –nr … -function StopService operations degrade the cluster monitoring
capabilities. SGeSAP has fallback mechanisms to monitoring routines that don’t require a
running startup agent, but the monitoring becomes less reliable without the agent. To reestablish
reliable monitoring capabilities and to reenable remote administration console access, the
cluster might chose to restart manually halted startup service agents immediately.
sapcontrol –nr … -function StopService operations for the software single points
of failure have the same effect as sapcontrol –nr … -function RestartService operations.
The cluster awareness of the sapstart service agent itself becomes activated by specifying the
SGeSAP cluster library in the profile of the corresponding SAP instance:
For SLES: service/halib=/opt/cmcluster/lib/saphpsghalib.so
For RHEL: service/halib=/usr/local/cmcluster/lib/saphpsghalib.so
With this parameter being active, the sapstart service agent notifies the cluster software of any
triggered instance halt. Planned instance downtime does not require any preparation of the cluster.
A running sapstart service agent needs to be restarted in order for the parameter to become
effective.
22 SAP cluster administration