Managing HP Serviceguard Extension for SAP for Linux, December 2013

NOTE: Activating package maintenance mode is a way to pause all SGeSAP service monitors
of a package immediately, but it can only be triggered with Serviceguard commands directly.
While package maintenance mode is active, failover of the package is disabled. Maintenance
mode also works for instances without HA library configured.
3.3 Change management
Serviceguard manages the cluster configuration. Among the vital configuration data are the
relocatable IP addresses and their subnets, the volume groups, the logical volumes and their
mountpoints. If you change this configuration for the SAP system, you have to change and reapply
the cluster configuration accordingly.
3.3.1 System level changes
Do not delete secure shell setup and mutual .rhosts entries of <sid>adm on any node.
Entries in /etc/hosts, /etc/services, /etc/passwd or /etc/group must be kept unified
across all nodes.
Directories below /export have an equivalent directory whose fully qualified path comes without
this prefix. These directories are managed by the automounter. NFS file systems get mounted
automatically as needed. Servers outside of the cluster that have External Dialog Instances installed
are set up in a similar way. See /etc/auto.direct for a full list of automounter file systems of
SGeSAP.
It enhances the security of the installation if the directories below /export are exported without
root permissions. The root user cannot modify these directories or their contents. With standard
permissions set, the root user cannot even see the files. If changes need to be done as root, the
equivalent directory below /export on the host the package runs on can be used as access point.
If the system is not configured correctly and if you attempt to login as <sid>adm user, the system
might hang. The reason is the /usr/sap/<SID>/SYS/exe command is in the path of the
<sid>adm user. Without local binaries, this directory contains a link to the /sapmnt/<SID>,
which is managed by the automounter file systems. If the package is down, the automounter cannot
contact the host that belongs to the relocatable IP address and the system hangs. To avoid this,
always retain a local copy of the executable on each node.
NOTE: If the database package with NFS services is halted, you may be able to log in as
<sid>adm unless you keep a local copy of the SAP binaries using sapcpe.
To allow proper troubleshooting, there is a more verbose package startup log is located in the
Serviceguard log directory. It should be checked first in case of problems. The level of information
can be adjusted by changing the log_level package parameter.
If problems with package startup remain, a general debug mode can be activated by creating an
SGeSAP debug flag file:
touch debug_<packagename> in the Serviceguard run directory, which is:
/usr/local/cmcluster/run on RHEL.
/opt/cmcluster/run on SLES.
The debug mode will allow the package to start until the SAP or database specific start commands
are reached. Any SAP instance or database instance startup will be skipped. Service monitors will
be started, but they do not report failures as long as the debug mode is turned on.
In this mode it is possible to attempt manual startups of the database and/or SAP software. All
rules of manual troubleshooting of SAP instances now apply. For example, it is possible to access
the application work directories of the SAP instance to have a look at the trace files.
3.3 Change management 29