[rrd-developers] Re: [rrd-users] Re: RRDtool "GMT-centric" problem?

Tobias Oetiker oetiker at ee.ethz.ch
Wed Jan 19 23:06:59 MET 2000

Today you sent me mail regarding [rrd-users] Re: RRDtool "GMT-centric" problem?:

*> - Change the whole concept of RRDtool

ahhh I like this one :-)

*> - Move your computer to UTC

this is a bit drastic ...

*> Without trying -so just to contribute for others to experiment- Have you
*> already tried to modify the timestamps you are feeding to RRDtool?
*> I think this will emulate the second option as described above.

exactly this should work beautifully ... 
*> Assume Europe, midnight, no DST in effect.  Time will be 948236400.
*> For UTC, this will be 23:00.  Add 3600 to 948236400 to get UTC midnight.
*> Use this new timestamp (948240000) to update the database.

yes ...

*> When extracting data from the database, again UTC should be used.
*> RRDtool will try and compensate for the timezone so this should be set
*> to UTC.  (TZ=UTC rrdtool graph --start 948240000 --end 948326400 ...)

yes, and on top of that you can save yourselv the math here and use at style
time just as if it was local time. 

*> If you store the samples in local time, you will be storing 2:00 twice
*> or never.  In the first case, you get an error, in the second case you
*> get a gap (which might be filled, depending on the DS settings).
*> In both cases, averages won't work properly because a day is not exactly
*> 24 hours.

I guess this can be neglected for the low resolution data people are talking
about in this case ... after all if you want to be exact you would use the
24h with long heartbeat aproach or even (oh horror) sample hourly ...

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