Using the Event Monitoring Service (November 1999)

Chapter 3 39
Defining a Monitoring Request
Setting the Polling Interval
Setting the Polling Interval
The polling interval specifies how often the resource monitor checks the
resource value. The polling interval is 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 too much 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. Some considerations
include:
• 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 10 seconds.
• 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.
Asynchronous monitors are event-driven, not polled. They generate
messages as events occur. Therefore if the resource is an asynchronous
monitor, the Polling Interval field displays n/a.
To set the Polling Interval:
1. Specify the quantity of time in the numbered field.
2. Select the unit of time from the unit of measure field list (seconds,
minutes, hours, day). The maximum value is one (1) day.