Graphite's whisper db creates .wsp files that have one or more internal archives that support some number of points at some resolution. The whisper-dump output is basically showing (index id: timestamp, value). In a fresh system most of the points would be emply showing 0,0 for timestamp,value. Even on a longer running system where the datapoints have passed the retention and wrapping would occur I have seen that the output is not always in order.
So for your question, if you see 0,0 as timstamp,value it simply means that index in the file hasn't been used yet or no data was submitted for a given index. If you are trying to relate this datapoints where Harvest didn't, or was unable to submit values, then whisper-fetch.py might be a better utility to use:
# whisper-fetch.py --help
Usage: whisper-fetch.py [options] path
-h, --help show this help message and exit
--from=_FROM Unix epoch time of the beginning of your requested interval
(default: 24 hours ago)
--until=UNTIL Unix epoch time of the end of your requested interval
--json Output results in JSON form
--pretty Show human-readable timestamps instead of unix times
Hope this helps!
Cheers, Chris Madden
Solution Architect - 3rd Platform - Systems Engineering NetApp EMEA (and author of Harvest)