[rrd-users] Parameter problem - was: LAST always returning zero

Wes wespvp at msg.bt.com
Wed Mar 12 18:09:10 CET 2008

Any luck on what might be going wrong in the CDEF?

I was concerned that if rrdtool last returned nothing, I could be reverting
to 'now', so I changed it to also print out the "rrdtool last" value it is
using.  This was not the problem - rrdtool last is always returning a valid
time stamp.

The picture is always the same, even if I push the --end time back over a
minute.  With --end being /10*10-2:

Rrdtool last: 1205340854
--end:        1205340848
LAST w/o IF:  1205340840
LAST with IF: 1205340860

Or, going back over 2 minutes with --end (/10*10-122):

Rrdtool last: 1205341417
--end:        1205341288
LAST w/o IF:  1205341280
LAST with IF: 1205341300

Is there any chance it is some sort of race condition with the updates
occurring at the same time as the graphs?  I'm assuming the code has
built-in locks to prevent such problems, and it seems unlikely such a race
condition would happen so often.


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