Useful stats (was Re: definitions for /proc/fs/xfs/stat)

[Nathan Scott <nathans@redhat.com>]

Hi Mark,

----- Original Message -----
> ...
> On a totally different topic, and if you like we can start a different
> thread on it, I'd be interested in adding some monitoring stats to collectl
> for xfs and could use some suggestions of what are the most important.

Did you receive any other feedback on this (offlist perhaps)?  I was kinda
hoping someone else would chime in, but can share our experiences with PCP
if it helps.

We provide options to record all xfs.* metrics & an alternative to record
just the core I/O stats (so log I/O and the file read/write metrics).  With
PCP one can record any subset at any rate, so those are just convenience /
default suggestions.

In terms of recording in collectl, not sure what the requirements/parameters
are for you but I'd suggest recording all the data (in save-to-disk mode),
and IIRC you've got brief/verbose reporting modes - I'd focus on the log,
file I/O and buffer I/O stats when being "brief", and expand out to showing
in-core inode/dquot stats, ail/transaction stats, dir/attr operation stats.
You might consider another very-verbose kinda view with all of the various
btree stats, but that may be going too far.

Note that these are all aggregate statistics, there has been on-and-off
discussion for many years about adding some per-filesystem XFS stats, but
to date that has not happened - perhaps someday it will, so keep that in
mind for collectl too I guess.

Also, be aware there is a separate file for quota metrics, for hysterical
raisins (/proc/fs/xfs/xqmstat).

HTH.

cheers.

--
Nathan

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