>>  Fedora comes with some cron jobs activated,
>>  in particular the cron.daily:

Indeed; not just Fedora, but most (all?) Linux
distros seem to come littered with all sorts of
cron jobs of questionable value.  The old UNIX
"minimalist" approach (letting people add stuff
if they wanted) seems to have been replaced with
a "let's try to do nearly everything" one, which
forces people to remove things they don't really
_want_ to have enabled.  But I'll stop ranting ...

My point is that we were burned by this, thanks
to SuSE's /etc/cron.daily/updatedb (performs the
same function as /etc/cron.daily/slocate.cron on
Fedora):  We'd seen horribly sluggish performance
on our PVFS filesystems once every day, until we
realized it was "updatedb" crunching through tens
of terabytes of files.  And it was even worse, as
"updatedb" fired off at the same time on close to
ninety systems at once!

The fix was obvious, namely adding "/pvfs" to the
"UPDATEDB_PRUNEPATHS" in /etc/sysconfig/locate (on
Fedora, it's "PRUNEPATHS" in /etc/updatedb.conf).

We didn't see any failures (network, PVFS, or any
other issues) per se; just awful performance until
we told the cron job not to descend into the /pvfs
hierarchy.

So if I were you, I'd still be a bit worried about
the fact the failures happened at all.  It might be
worth doing some controlled heavy pounding of your
PVFS hierarchy (e.g. just a massive "find" to walk
the entire PVFS filesystem; or better, a bunch of
them going on simultaneously, launched from a lot
of different systems) to see whether the problems
recur ...
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