<div dir="ltr"><div class="gmail_extra">On 22 February 2014 03:49, ENTRESSANGLE, ERIC (ERIC) <<a href="mailto:eric.entressangle@alcatel-lucent.com">eric.entressangle@alcatel-lucent.com</a>> wrote:</div><div class="gmail_extra">
[...]<br>> Each minute based on the full minute (i.e 18:23:00, 18:24:00), the measuring device writes the counter value in a file. Then the measuring device resets the counter value to 0. So the counter value at 18:24:00 is the number of opened sessions between 18:23:00 and 18:24:00. And in our case, the 9 sessions are created between 18:23:00 and 18:24:00.<br>
<br></div><div class="gmail_extra">Ah. In that case what your measurements already have a timestamp associated with them. For accuracy, you should use that timestamp (18:24:00 in this case).</div><div class="gmail_extra">
<br></div><div class="gmail_extra">> But cacti’s poller retrieves the counter value from the file at 18:24:15 (because we put a tempo to be sure the whole file is written, and anyway there are a lot of counters to retrieve, so the polling will never occur exactly at 18:24:00). So the rrdtool update timestamp is 18:24:15, whereas in fact the timestamp should be 18:24:00, because it is the counter value at 18:24:00 which is retrieved.<br>
<br>rrd allows you to specify the timestamp to use for updates which for your case you could do like this;</div><div class="gmail_extra"><br></div><div class="gmail_extra">rrdtool update my.rrd $[ `date +%s` / 60 * 60 ]:v1:v2:...</div>
<div class="gmail_extra"><br></div><div class="gmail_extra">Though probably using the timestamp of the file would be more accurate since you could occasionally somehow have missed updates;</div><div class="gmail_extra"><br>
</div><div class="gmail_extra">rrdtool update my.rrd $[ `stat -c "%Y" /my/infile` / 60 * 60 ]:v1:v2:...<br></div><div class="gmail_extra"><br></div><div class="gmail_extra">I don't know cacti, so I don't know if it allows you to specify the timestamp, or how to do it.</div>
<div class="gmail_extra"><br></div><div class="gmail_extra">Is there some raw session counter you could read directly instead of this counter file approach? Alternatively you could have your measuring device directly update rrd at each session, which would be the most accurate way to do it. rrd can probably do a better job of normalizing this data into sessions/minute than your measuring device.</div>
<div class="gmail_extra"><br>--<br>Donovan Baarda <<a href="mailto:abo@minkirri.apana.org.au">abo@minkirri.apana.org.au</a>>
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