Brocade Fabric Watch Administrator's Guide Supporting Fabric OS v6.0.0 (53-1000601-01, October 2007)

14 Fabric Watch Administrator’s Guide
53-1000601-01
Configuring events
1
When you set a time base to a value other than none, there are two main points to remember when
configuring events:
• Fabric Watch triggers an event only if the difference in the data value exceeds the preset
threshold boundary limit.
• Even if the current data value exceeds the threshold, Fabric Watch does not trigger an
event if the rate of change is below the threshold limit.
The following examples illustrate each point.
Example1: Triggering an event
Figure 4 shows a sample graph of data obtained by Fabric Watch (the type of data is irrelevant to
the example). A high threshold of 2 is specified to trigger an event. A time base of minute is
defined. An event occurs only if the rate of change in the specific interval (one minute in this
example) is across the threshold boundary. It should be either higher than the high threshold limit
or lower than the low threshold limit.
As illustrated on the tenth sample, the counter value changes from 0 to 1; hence calculated rate of
change is 1 per minute. At the thirteenth sample, the rate of change is 2 per minute. The rate of
change must be at least 3 per minute to exceed the event-triggering requirement of 2, which is met
on the eighteenth sample.
FIGURE 4 Event trigger
Example 2: Not triggering an event
Figure 5 uses the same data to illustrate a case in which a threshold is exceeded without triggering
an event. In this case, the calculated rate of change in the data value is always less than or equal to
the high threshold of 2.
At the tenth sample, the rate of change is one per minute. At the fourteenth, twenty-first, and
twenty-fifth sample, the rate of change remains equal to the high threshold of 2. In this case, Fabric
Watch does not trigger an event even though the absolute value of the counter reaches 4, which is
well above the high threshold.