Grafana showing wrong data in graph for disk usage

Question

Grafana is showing wrong disk use percentage in graph. Currently my glusterfs disk usage is 8%, but on graph its showing 7%.

Below is the metrics which I am currently using.

{ "hide": true, "target": "sumSeries(collectd.gls--01.df-gluster.df_complex-used)", "refId": "A" }, { "hide": true, "target": "sumSeries(collectd.gls--01.df-gluster.df_complex-{free,used})", "refId": "B" }, { "hide": false, "target": "asPercent(#A, #B)", "refId": "C

Also I am unable to see percent_bytes-used metrics in collectd directory.

Answer 1

Depending on the ReportReserved in your collectd configuration you might need to take account for reserved disk space. If it is true (default on collectd > 4) you will have to change your second metric to: 'df_complex-{free,used,reserved}'

Answer 2

I am unable to save the json file. If I am making changes in the file after some time it is getting back to the same values.