Date: Tue, 9 Mar 2010 11:58:10 +0100 From: Stefan Bethke <stb@lassitu.de> To: Peter Jeremy <peterjeremy@acm.org> Cc: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: Many processes stuck in zfs Message-ID: <D160BCD0-CBD9-492D-8512-044DC03E2D6E@lassitu.de> In-Reply-To: <20100309105355.GD3978@server.vk2pj.dyndns.org> References: <864468D4-DCE9-493B-9280-00E5FAB2A05C@lassitu.de> <20100309105355.GD3978@server.vk2pj.dyndns.org>
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Am 09.03.2010 um 11:53 schrieb Peter Jeremy: > On 2010-Mar-09 10:15:53 +0100, Stefan Bethke <stb@lassitu.de> wrote: >> Over the past couple of months, I've more or less regularly observed machines having more and more processes stuck in the zfs wchan. The processes never recover from that, > > How long have you waited? Many hours, sometimes up to 48 hours (when I didn't notice the stuck processes at first). > There seems to be a problem with low free memory handling that causes ZFS > to turn into cold molasses. The work-around is to run a program that > allocates a decent size chunk of memory and then exits. The original > suggestion was something like: > perl -e '@x = (0) x 1000000;' > I've written a short program that allocates and dirties ~100MB and then > exits and run it from cron. I'll try that the next time I encounter the stuck processes. I'm recording ZFS ARC stats with munin, would I be able to identify such a low memory situation from there? Would it make sense to monitor other stats? Thanks, Stefan -- Stefan Bethke <stb@lassitu.de> Fon +49 151 14070811
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