HP StorageWorks Clustered File System 3.6.0 Windows Storage Server Edition Administration Guide (403103-005, January 2008)

Chapter 17: Configure Device Monitors 211
Custom Device Monitor
A
CUSTOM device monitor can be used if the built-in device types are not
sufficient for your needs. Custom device monitors can be particularly
useful when integrating HP Clustered File System with a custom
application.
When you create a
CUSTOM monitor, you will need to supply the probe
script. 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. HP Clustered File
System interprets the non-zero exit status as a failure of the device and
takes the appropriate action.
See “Advanced Monitor Topics” on page 226 for information about
developing probe scripts for custom monitors and integrating monitors
with custom applications.
Device Monitors and Failover
When a device monitor is configured for failover and the probe reports a
failure, HP Clustered File System attempts to relocate any virtual hosts
that depend on the monitored device to a healthier server:
• For a single-active monitor, the active virtual hosts are failed over to a
backup server and the monitor becomes active on that server. See the
“Device Monitor Activeness Policy,” below, for details about where
the monitor will be made active.
• For a multi-active monitor, the virtual hosts are failed over to a backup
server. The monitor remains active on the same set of servers.
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 .