3.5.1 Matrix Server Administration Guide

Chapter 13: Configure Service Monitors 231

Scripts

Service monitors can optionally be configured with scripts that are run at

various points during matrix operation. The script types are as follows:

Recovery script. Runs after a monitor probe failure is detected, in an

attempt to restore the service.

Start script. Runs as a service is becoming active on a server.

Stop script. Runs as a service is becoming inactive on a server.

When a monitor is instantiated for a service (because the ClusterPulse

daemon is starting or the configuration has changed), Matrix Server

chooses the best server to make the service active. The Start script is run

on this server. On all other servers configured for the monitor, the Stop

script is run to ensure that the service is not active.

Start scripts must be robust enough to run when the service is already

started, without considering this to be an error. Similarly, Stop scripts

must be robust enough to run when the service is already stopped,

without considering this to be an error. In both of these cases, the script

should exit with a zero exit status. This behavior is necessary because

Matrix Server runs the Start and Stop scripts to establish the desired

start/stop activity, even though the service may actually have been started

by something other than Matrix Server before ClusterPulse was started.

The Start and Stop scripts must also handle recovery from events that

may cause them to run unsuccessfully. For example, if the system runs

out of swap space while running a Start script, the script will fail and exit

non-zero. The service could then become active on another server,

causing the Stop script to run on the original server even though the Start

script did not complete successfully.

To configure scripts from the command line, use these options:

--recoveryScript <script> --recoveryTimeout <seconds>

--startScript <script> --startTimeout <seconds>

--stopScript <script> --stopTimeout <seconds>

Use Custom Scripts to Modify Start/Stop Activities

Some built-in monitors perform starting or stopping activities. If you

need to take an action before or after the starting or stopping activity, you