HP StorageWorks Fabric OS 5.0.0 Fabric Watch User Guide (AA-RW1TA-TE, May 2005)

Fabric Watch concepts34
Setting time base to none
If you set a time base to none , Fabric Watch compares a data value against a threshold
boundary level. When the absolute value of the measuring counter exceeds the threshold
boundary, an event is triggered.
Figure shows a high limit of 65 degrees Celsius placed on a counter measuring temperature.
During each sample period, Fabric Watch measures the temperature is measured and
compares it against the high threshold. If the measured temperature exceeds the high
threshold, it triggers an event.
Figure 3 Time base set to none
Specifying a time base
If you specify a time base value other than none ( seconds , minute , hour , or day ), Fabric Watch
does not use the current data value. Instead, it calculates the difference between the current
data value and the data value as it existed one time base ago. It compares this difference to
the threshold boundary limit.
For example, if you specify the time base
minute , Fabric Watch calculates the counter value
difference between two samples a minute apart. It then compares the difference (current data
value – data value one minute ago) against the preset threshold boundary.
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.