Using EMS HA Monitors

Chapter 1 23
Installing and Using EMS
Using EMS HA Monitors
NOTE Updated monitors may have new status values that change the meaning of your
monitoring requests, or generate new alerts.
For example, assume you have a request for notification if status > 3 for a resource
with a values range of 1-7. You would get alerts each time the value equaled 4, 5, 6,
or 7. If the updated version of the monitor has a new status value of 8, you would see
new alerts when the resource equalled 8.
What is a Polling Interval?
The polling interval determines the maximum amount of elapsed time before a
monitor knows about a change in status for a particular resource. The shorter the
polling interval, the more likely you are to have recent data. However, depending on
the monitor, a short polling interval may use more CPU and system resources. You
need to weigh the advantages and disadvantages between being able to quickly
respond to events and maintaining good system performance.
The minimum polling interval depends on the monitor’s ability to process quickly.
For most resource monitors the minimum is 30 seconds. Disk monitor requests can
be as short as 1 second.
MC/ServiceGuard monitors resources every few seconds. You may want to use a
short polling interval (30 seconds or less) when it is critical that you make a quick
failover decision.
You may want a polling interval of 5 minutes or so for monitoring less critical
resources.
You may want to set a very long polling interval (4 hours) to monitor failed disks
that are not essential to the system, but which should be replaced in the next few
days.
Which Protocols Can I Use to Send Events?
You specify the protocol the EMS framework uses to send events in the Notify via:
section of the screen in Figure 1-6. The options are:
• opcmsg ITO sends messages to ITO applications via the opcmsg daemon. EMS
defines normal and abnormal differently for each notification type:
• Conditional notification defines all events that meet the condition as
abnormal, and all others as normal.
• Change notification defines all events as abnormal.
• Notification at each polling interval defines all events as normal.