| Title: | DECmcc user notes file. Does not replace IPMT. |
| Notice: | Use IPMT for problems. Newsletter location in note 6187 |
| Moderator: | TAEC::BEROUD |
| Created: | Mon Aug 21 1989 |
| Last Modified: | Wed Jun 04 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 6497 |
| Total number of notes: | 27359 |
Hello, I have the following question on how alarmin of statistics actually works: There is an example in the update alarms and notifications manual on page 5-30. In this example the statistic calculation duration is 2 minutes, the polling interval of the alarm is 5 minutes. 2 4 6 8 10 12 statistic calculation finished | | | | | | ----------------------------------------- ^ ^ | | alarm poll alarm poll If I am correct the above picture outlines the scenario. Take the first alarm poll as an example. Before this poll the statistic was calculated twice. Does the alarm poll only look at the calculated value that was finished at 4 minutes, or does it look at both the 2 minute and 4 minute value? And if it only looks at the 4 minute value, what is the sense of calculating the statistic every 2 minutes? Second question, will I run into grave problems if I set the alarm polling interval and the duration interval to be the same? Thanks in Advance, Julie Ann
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 2933.1 | Misunderstanding | TOOK::ANWARUDDIN | Anwar | Tue May 05 1992 15:18 | 26 |
I think there is a misunderstanding of how alarming of statistics works.
Once again let's take the example mentioned in .0 ( taken from page 5-30
of the Alarms & Notifications Use Manual). The Alarm polling interval
is 5 mins. The Duration is 2 mins. This means every 5 mins., the Performance
Analyzer is called to compute the statistic, which is being monitored, for
a duration of 2 mins. as shown below:
A+2 B+2 C+2 <------- Statistic is gotten at these times
| | |
x---+-----x---+-----x---+-----x--
| | | |
A B C D <------ PA is called at these times
5 min 5 min 5 min
As you can see, the rule expression evaluations take place a little after A+2,
B+2, C+2 etc and if an evaluation is true the rule fires at that instant.
The thing to remember is that the Alarms FM calls the Performance Analyzer every
'n' minutes to calculate the statistic for the specified duration. The evaluation
of the expression begins at the end of the 'duration' after the Performance
Analyzer is done computing the statistic.
Regarding your second question, it is a good idea to set the Alarm polling interval
slightly larger (by 1 or 2 mins) than the duration to allow for the overhead in PA
& Alarms. Otherwise you might miss some intermediate polls.
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