Managing HP Serviceguard Extension for SAP for Linux, December 2013

standard administration commands issued manually from outside of the cluster environment. These
commands can be sapcontrol operations triggered by SAP system administrators, that is,
sidadm users who are logged in to the Linux operating system or remote SAP basis administration
commands via the SAP Management Console (SAP MC) or commands via SAP’s plugin for Microsoft
Management Console (SAP MMC).
The SAP Netweaver 7.x startup framework has a host control agent software process (hostctrl) that
runs on each node of the cluster and a sapstart service agent software process (sapstartsrv) 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.
NOTE: startsap and stopsap operations must not be used in clusters that have SAP software
monitors configured. sapcontrol operations must be used instead. For more information on how
to use sapcontrol with old SAP releases, see SAP note 995116.
If SAP 4.x and 6.x startsap and stopsap commands get executed, any configured monitor will not
be able to judge whether an instance is down because of a failure or because of a stopsap
operation. SGeSAP will therefore trigger an instance restart or an instance failover operation in
reaction to execution of the stopsap script. The SAP Netweaver 7.x standard administration
commands communicate with the SGeSAP environment.
The startsap/stopsap scripts are not recommended by SAP as of Netweaver 7.x and must
not be used anymore. It is recommended to configure startup framework agents for older SAP
releases, too.
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 <instnr> –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 monitors to
continue to operate reliably it is thus mandatory that the sapstart services remain running.
• sapcontrol –nr <instnr> -function StopService operations degrade the cluster
monitoring capabilities. SGeSAP has fallback mechanisms in the monitoring routines so that
do not require a running startup agent, but the monitoring becomes less reliable without the
agent. To reestablish reliable monitoring capabilities and to enable remote administration
console access, the cluster might chose to restart manually halted startup service agents
immediately.
sapcontrol –nr <instnr> -function StopService operations for the software
single points of failure have the same effect as sapcontrol –nr <instnr> -function
RestartService operations.
The cluster awareness of the sapstart service agent itself are 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
26 SAP cluster administration