[rrd-users] Re: understanding RRD's; 5 questions

Dave Bodenstab imdave at mcs.net
Sat Feb 24 01:31:08 MET 2001

> > Seems to me that with this, I could just adjust my times
> > in such a way that my local-timed data would be plopped
> > into the correct utc-time time slots.
> Last Sunday in March, 02:30 local time.
> Last Sunday in October, 02:30 local time.
> How would you handle these two times?  (given the fact that
> daylight saving time starts at 02:00 and ends at 03:00)
> I don't think there is a better solution than to use hourly
> RRAs.  You want hourly precision, don't ask for daily precision.

Since I just picked up the rrdtool package and am just beginning
to play with it, I'll have to defer to you since you know the
system far better than I.

Probably my example of a daily statistics for procs/user is
unrealistic, but it was the first thing that came to mind
that I have raw data with which to test rrd; I think I'll try
taking the output of netstat -i and feeding a test rrd hourly...
perhaps that will make more sense.

But I'll try to explain what I was thinking one more time, then
I'll drop it...  If one added a UTC keyword to the syntax for
at-style times, and its effect was to convert the time-spec
without applying local time corrections, then wouldn't my times
come our correctly in all cases?  After all, UTC time doesn't
have daylight savings.  Admittedly, if I use my local time
and just tack on a UTC, I'll skip an hour in the spring and
duplicate an hour in the fall -- only if I was entering data
on the hour -- I think I could live with that since it makes
entering the data so much easier.  In the cases where I am
entering data once per day, just avoiding 2-3am solves that
problem -- and yes, my data point would be for 23h in the spring
and 25h in the fall -- but this is correct with respect to 
local time.

Anyway, it just seems that since rrd wants utc times, it would
be nice to have a way to enter them directly without dealing
with the local time issue.

Thanks for your consideration.

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