There are several things happening here, but basically the problem is that you have misconfigured graphite (or at least, configured it in a way that makes it do things that you aren't expecting!)
Specifically, you should set xFilesFactor = 0.0
in your storage-aggregation.conf file. Since you are new at this, you probably just want this (mine is in /opt/graphite/conf/storage-aggregation.conf):
[default]
pattern = .*
xFilesFactor = 0.0
aggregationMethod = average
The graphite docs describe xFilesFactor like this:
xFilesFactor should be a floating point number between 0 and 1, and specifies what fraction of the previous retention level’s slots must have non-null values in order to aggregate to a non-null value. The default is 0.5.
But wait! This wont change existing statistics! These aggregation settings are set once per metric at the time the metric is created. Since you are new at this, the easy way out is to just go to your whisper directory and delete the prior data and start over:
cd /opt/graphite/storage/whisper/my/
rm key.wsp
your root whisper directory may be different depending on platform, etc. After removing the data files graphite should recreate them automatically upon the next metric write and they should get your updated settings (dont forget to restart carbon-cache after changing your storage-aggregation settings).
Alternatively, if you need to keep your old data you will need to run whisper-resize.py
against your whisper (.wsp) data files with --xFilesFactor=0.0 and also likely all of your retention settings from storage-schemas.conf (also viewable with whisper-info.py
)
Finally, I should add that the reason you get non-null data in your first query, but null data in your second is because graphite will try to pick the best available retention period from which to serve your request based on the time window you requested. For the smaller window, graphite is deciding that it can serve your request using the highest precision data (i.e., non aggregated) and so you are seeing your raw metrics. For the longer time window, graphite is finding that the high precision, non-aggregated data is not available for the entire window -- these periods are configured in storage-schemas.conf -- so it skips to the next highest-precision data set available (i.e. first aggregation tier) and returns only aggregated data. Because your aggregation config is writing null data, you are therefore seeing null metrics! So fix the aggregation, and you should fix the null data problem. But remember that graphite never combines aggregation tiers in a single request/response, so anytime you see differences between results from the same query when all you are changing is the from / to params, the problem is pretty much always due to aggregation configs.