[mrtg] strange graphing errors

[Steve Shipway]

> i don't see any changes in config, and my data is being updated, just 
> not reflected in the graphs. the only recent thing occuring on this
server 
> is a tzdata patch for the new daylight saving time.

No embedded images appeared in the posting, so we cant see your graph
image.

Since the thing you updated was a tzdata patch, and MRTG/RRD is heavily
dependent on time synchronisation, then there is a good chance that
these are connected.  Maybe the updating time now is not matching
reality?  Also, check your current time/date is correct (did the patch
cause the apparent 'now' time to change?) and that the system's current
timezone offset is being calculated correctly - RRD uses the absolute
GMT time for logging and reports in local time.  You may have your
universal time wrong, and your timezone wrong, but the cululative effect
gives a correct local time - this would screw up MRTG graphs but would
make 'date' report the correct time.

I have no way of testing this as I'm not in your zone and dont have the
patch.  Probably some US-based people on the list can help check this.

Steve

--
Steve Shipway
ITSS, University of Auckland 
(09) 3737 599 x 86487
s.shipway at auckland.ac.nz