Managing Serviceguard Extension for SAP, December 2007

SAP Supply Chain Management
SGeSAP Package Configuration
Chapter 4230
Service Monitoring
SAP recommends the use of service monitoring in order to test the
runtime availability of liveCache processes. The monitor, provided with
SGeSAP, periodically checks the availability and responsiveness of the
liveCache system. The sanity of the monitor will be ensured by standard
Serviceguard functionality.
The liveCache monitoring program is shipped with SGeSAP in the
saplc.mon file. The monitor runs as a service attached to the lc<LCSID>
Serviceguard package.
If the monitor recognizes the liveCache to be unavailable, it will promote
the hot standby system to become the new master. If no hot standby is
available, the monitor will try to restart liveCache on the node it is
currently running. If this does not succeed, the runtime operating system
resources of liveCache are cleaned up and another local restart attempt
is made. If this still does not bring liveCache back to work and a failover
package with storage option 1,2 or 3 is used, Serviceguard will switch the
package and try to restart the same instance on different hardware.
Monitoring begins with package startup. At this point, the monitor will
make sure, that liveCache is working only up to the point that is
specified in LCSTARTMODE. For example, if LCSTARTMODE=OFFLINE is set
in sap.config, only the vserver processes will be part of the monitoring.
Still, the monitor detects any manual state change of liveCache. By
subsequent manual operations, liveCache will be entering cold state and
finally warm state, which the monitor automatically detects. As soon as
the liveCache reaches the warm state once, the monitoring increases its
internal monitoring level to the same state.
As any SGeSAP package, the lc package will skip SAP specific startup
steps when during startup a file called debug is found in either
/etc/cmcluster/<LCSID> or /etc/cmcluster. This is useful for
debugging purposes to allow access to the log files placed on shared
logical volumes if a package does not start up to its full extend. The lc
monitor is started regardless of the availability of a debug file. The
monitor will detect the existence of the file and will enter a pause mode
until it is removed. This is valid not only during package startup, but
also at runtime. As a consequence, the monitoring of a fully started
package will be paused by the global debug file.