Managing Serviceguard 13th Edition, February 2007

Configuring Packages and Their Services
Creating the Package Control Script
Chapter 6290
echo 'Starting pkg1' >> /tmp/pkg1.datelog
test_return 51
}
# This function is a place holder for customer defined functions.
# You should define all actions you want to happen here, before the service is
# halted.
function customer_defined_halt_cmds
{
# ADD customer defined halt commands.
: # do nothing instruction, because a function must contain some command.
date >> /tmp/pkg1.datelog
echo 'Halting pkg1' >> /tmp/pkg1.datelog
test_return 52
}
# END OF CUSTOMER DEFINED FUNCTIONS
Adding Serviceguard Commands in Customer Defined Functions
You can add Serviceguard commands (such as cmmodpkg) in the
Customer Defined Functions section of a package control script.
However, these commands must not interact with the package itself.
If you do run Serviceguard commands from the package control script,
they must be run as background processes, otherwise the package will
hang. This is done by adding a “&” (ampersand) to the end of the
command line. For example: cmmodpkg -d <package-name> &
If a Serviceguard command interacts with another package, then you
need to check all packages with Serviceguard commands for the
possibility of a command loop. For instance, a command loop might occur
under the following circumstances. Suppose Pkg1 does a cmmodpkg -d of
Pkg2, and Pkg2 does a cmmodpkg -d of Pkg1. If both Pkg1 and Pkg2
start at the same time, Pkg1 tries to cmmodpkg Pkg2. However, that
cmmodpkg command has to wait for Pkg2 startup to complete. Pkg2 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 always specify a
RUN_SCRIPT_TIMEOUT and a HALT_SCRIPT_TIMEOUT for all packages,
especially packages that use Serviceguard commands in their control
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.