Managing Serviceguard A.11.20, March 2013

{
sg_log 5 "start_command"
# log current PEV_MONITORING_INTERVAL value, PEV_ attribute can be changed
# while the package is running
sg_log 0 "PEV_MONITORING_INTERVAL for $SG_PACKAGE_NAME is $PEV_MONITORING_INTERVAL"
return 0
}
function stop_command
{
sg_log 5 "stop_command"
# log current PEV_MONITORING_INTERVAL value, PEV_ attribute can be changed
# while the package is running
sg_log 0 "PEV_MONITORING_INTERVAL for $SG_PACKAGE_NAME is $PEV_MONITORING_INTERVAL"
return 0
}
typeset -i exit_val=0
case ${1} in
start)
start_command $*
exit_val=$?
;;
stop)
stop_command $*
exit_val=$?
;;
validate)
validate_command $*
exit_val=$?
;;
*)
sg_log 0 "Unknown entry point $1"
;;
esac
exit $exit_val
Using Serviceguard Commands in an External Script
You can use Serviceguard commands (such as cmmodpkg) in an external script run from a package.
These commands must not interact with that package itself (that is, the package that runs the external
script) but can interact with other packages. But be careful how you code these interactions.
If a Serviceguard command interacts with another package, be careful to avoid command loops.
For instance, a command loop might occur under the following circumstances. Suppose a script
run by pkg1 does a cmmodpkg -d of pkg2, and a script run by pkg2 does a cmmodpkg -d
of pkg1. If both pkg1 and pkg2 start at the same time, the pkg1 script now tries to cmmodpkg
pkg2. But that cmmodpkg command has to wait for pkg2 startup to complete. The pkg2 script
tries to cmmodpkg pkg1, but pkg2 has to wait for pkg1 startup to complete, thereby causing a
command loop.
To avoid this situation, it is a good idea to specify a run_script_timeout and
halt_script_timeout (page 240) for all packages, especially packages that use Serviceguard
commands in their external scripts. If a timeout is not specified and your configuration has a
command loop as described above, inconsistent results can occur, including a hung cluster.
Determining Why a Package Has Shut Down
You can use an external script (or CUSTOMER DEFINED FUNCTIONS area of a legacy package
control script) to find out why a package has shut down.
Serviceguard sets the environment variable SG_HALT_REASON in the package control script to
one of the following values when the package halts:
• failure - set if the package halts because of the failure of a subnet, resource, or service it
depends on
• user_halt - set if the package is halted by a cmhaltpkg or cmhaltnode command, or
by corresponding actions in Serviceguard Manager
• automatic_halt - set if the package is failed over automatically because of the failure of
a package it depends on, or is failed back to its primary node automatically
(failback_policy = automatic)
Package Configuration Planning 159