Info about how PMM evaluate the metrics for a given filesystem

Percona Monitoring and Management (PMM) PMM 2.x
1

Description:

Metrics usage for a given filesystem.

Hi all, on the pmm dashboard for a given mountpoint i see the values for Free,Used and Usage%

If i extract the metrics about the same filesystem with curl using:
node_filesystem_avail_bytes,
node_filesystem_size_bytes,
node_filesystem_free_bytes
and i calculate free% as 100*[@UsedSize]/([@AvailableSize]+[@UsedSize]) i get a different value than the one calculated on the dashboard.
I know that differs because one should take into account the space reserved for root user.
How can i obtain the same usage% shown on the dashbord using the available metrics?

Steps to Reproduce:

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Version:

PMM 2.x

Logs:

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Expected Result:

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Actual Result:

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Additional Information:

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2

Hi, how are you calculating used size though?

node_filesystem_avail_bytes excludes reserved blocks (i.e., only reports space available to non-root users) so you might need something like the one below to match the dashboard:

100 * (1 - free_bytes / size_bytes)

3

Thank you Michael, i was using free bytes instead than available bytes
Now calculating the free % i’m getting the same values shown on the dashboard,
even though those values are a little different from those shown by df command on the hosts the result is now coherent.