3.1.2 Matrix Server Administration Guide

Chapter 13: Configure Device Monitors 176

Disk Device Monitor

The DISK device monitor can be used to monitor a disk device. It

periodically attempts to read the first block of the disk partition that you

specify to determine whether the disk is operating normally.

Custom Device Monitor

A CUSTOM device monitor can be particularly useful when integrating

Matrix Server with a custom application. Custom monitors can be

configured to be either single-active or multi-active.

You must supply the probe script for the custom monitor. In the script,

probe commands should determine the health of the device as necessary.

If the device is operating normally, the probe script should exit with exit

status zero. If the device is not operating normally, the probe script

should exit with a non-zero exit status. Matrix Server will interpret the

non-zero exit status as a failure of the device, and take the appropriate

action.

See “Advanced Topics” on page 209 for information about developing

probe scripts for custom monitors and integrating monitors with custom

applications.

Device Monitors and Failover

When you create a device monitor, you specify a list of servers on which

the device monitor will operate. The servers are placed in order: primary,

backup #1, backup #2, and so on. ClusterPulse considers the status and

enablement of the servers when determining where to activate a device

monitor.

Device Monitor Activeness Policy

ClusterPulse uses the following device monitor activeness policy to

determine the server or servers where it will make a device monitor

active. The policy described here is accurate for this release but it may

change in future releases or be modified by PolyServe Solution Packs.

The device monitor activeness policy decision is made as follows:

1. If the device monitor on a specific server is disabled, then the device

monitor will not be made active on that server.