scott.list wrote: > > > The question was: how to prevent this normalizing. The only thing > to > > do is to make sure > > > normalizing becomes a no-op. > > Alex: Can you elaborate on the above? I believe this is realted to a > questions I asked awhile back but got no answers. I figured my > question wasn't worded well enough. Anyway, any elaboration > appreciated. > > I'm doing all I can to ensure my data is hitting the rrd at the proper > times but I'm still seeing occasional normalizations. Any example or > suggestions on how to insure it becomes no-op, or exactly what you > mean?
faq site: http://faq.mrtg.org/information.html scroll down to "Problem 3: irregular sample periods" Each interval is "m" seconds large. RRDtool will always store (so: after normalizing the data) a complete interval. The first interval ever started at time 0, the second interval starts at 1*m, the third interval starts at 2*m. ---> "n*m" where n is an integer and "m" is the lenght of an interval (defined by --step). Current time: 1028765858 For intervals of 86400 seconds (one day) this time belongs to interval int(1028765858/86400) to int(1+ 1028765858/86400). This means n=11907 and m=86400 --> time 1028764800 to 1028851200. For *my* timezone this is august 8th, 02:00 to august 9th, 02:00. For others this may be different. If I update now, or if I update at any other time than 1028851200, RRDtool will normalize the rates. Only when I update at 1028851200 there's nothing to do ---> no-op. Midnight *my* timezone was 1028757600. When divided by 86400 this has a remainder. The key here to understand is that timezones are (for the biggest part of the world anyway) a whole number of hours away from UTC. Also think about daylight saving; where I live the time in winter is only one hour ahead of UTC, during the summer it is two hours away from UTC. To be able to update at midnight, winter *and* summer, I need to be able to make "n*m" result in midnight. There are many combinations possible for "n" and "m" but setting 24 (sometimes 23 or 25) intervals of 3600 seconds in one update command is the most effective -> m==3600. august 9th, midnight my timezone is 1028757600. 1028757600/3600 is 285766 remainder 0. This is therefore "the right time" for an RRD with "--step 3600". The rate is already there at the end of an interval and no normalization will occur --> no alteration of the rate I enter. Just make sure RRDtool allows for setting the rate once per day, this means the heartbeat *must* be 25*3600 or higher (25 because of the change in daylight saving when there *are* 25 hours in a day). -- __________________________________________________________________ / [EMAIL PROTECTED] [EMAIL PROTECTED] \ | work private | | My employer is capable of speaking therefore I speak only for myself | +----------------------------------------------------------------------+ | Technical questions sent directly to me will be nuked. Use the list. | +----------------------------------------------------------------------+ | http://faq.mrtg.org/ | | http://rrdtool.eu.org --> tutorial | +----------------------------------------------------------------------+ -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-users WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
