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

Triggering a package halt is possible whether instances of the package are currently halted or
not. The operation causes the cluster to loose information about all the instances that were manually
halted during the package run.
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.
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.
System level changes
Never delete mutual .rhosts entries of <sid>adm on any of the nodes. Never delete the secure shell
setup.
Do not delete the secure shell setup. Do not delete mutual .rhosts entries of <sid>adm on any
of the nodes, if they still exist.
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 badly configured, it might be possible that the system hangs if a logon is attempted
as <sid>adm user. The reason for this is, that /usr/sap/<SID>/SYS/exe is part of the path
of <sid>adm. Without local binaries, this directory links to /sapmnt/<SID>, which is handled
by the automounter. The automounter cannot contact the host belonging to the relocatable address
that is configured because the package is down—the system hangs. To avoid this, always keep
local copies of the executables.
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 verbose package startup log in the Serviceguard log
directory. It must be checked first in case of trouble. 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_<pacakagename> in the Serviceguad run directory location, which is:
/usr/local/cmcluster/run on RHEL.
/opt/cmcluster/run on SLES.
Change management 25