amrd disk performance drop after running under high load

[Thomas Hurst]

* Alexey Popov (lol at chistydom.ru) wrote:

> So I can conclude that FreeBSD has a long standing bug in VM that
> could be triggered when serving large amount of static data (much
> bigger than memory size) on high rates. Possibly this only applies to
> large files like mp3 or video.

I've seen highly dubious VM behavior when reading large files locally;
the system ends up swapping out a small but significant amount of
various processes, even very small recently active ones like syslogd,
for no apparant reason:

  http://lists.freebsd.org/pipermail/freebsd-stable/2007-September/036956.html

I've also seen dubious IO behavior from amr(4), where access to one
array will interfere with IO from an independent set of spindles that
just happen to be attached to the same card:

  http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/114438

Given the blank looks I've received every time I've mentioned these
things I'm guessing they aren't seen by others all that often, but maybe
one or both are vaguely relevent to your situation.

-- 
Thomas 'Freaky' Hurst
    http://hur.st/