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filesystem fill up time #29
One reason why I still have the host stats dashboard is because it has this neat little table of "Filesystem Fill Up Time" which (tries to?) compute the time at which the filesystem will fill up.
I don't think it's working very well because the results are just off here. But it got me thinking about how this could be implemented and whether you'd be interested in adding this to the dashboard...
The hosts stats dashboard uses this formula:
This blog post suggests instead just using the derivative as a base:
I would suggest using
I'm not very familiar with Prometheus formulas, so I'm not sure how it works. I suspect it just doesn't, because it gives me negative numbers here (they don't show up) or absurd estimates (
Yet this could be an interesting addition.
pushed a commit
Feb 13, 2019
Thanks for the upgrade proposal, it looks nice.
I've been testing both formulas and the first one seems to work better, but take note that it only reports content if the values are "> 0", if not, the box it will be empty.
The second formula doesn't report good values, in my testing lab, 11ms in a filesystem without changes. In any case, if you want to test it, the corrected formula is:
Please, check the last commit on node-exporter-full.json it have the new box under "CPU Memory Net Disk", you can move it to other place without problem.
that looks okay, but I still find some strange things going on. take this graph for example:
This gives the following table:
There are many problems here, the first of which of course is the host isn't continuously available (it's a workstation, and it shuts down once in a while). But then the other filesystems (I'm specifically interested in
Here's the raw unprocessed output from Prometheus doing the query (
Notice how Prom thinks those numbers are negative. I would also point out that it's somewhat unlikely that (for example)
So I'm not sure those derivatives are that useful in predicting the future. There might be something fishy going on here... I find it especially strange that the estimates would vary based on the Grafana time range...
Another example of the estimate failing, on my home server:
Here's the absolute numbers:
As you can see,
In fact, maybe we should use the infinity symbol (
Could you check if predict_linear function return results in your case: