Date: Fri, 29 Jul 2005 16:44:52 +0200 From: Marc Olzheim <marcolz@stack.nl> To: Julian Elischer <julian@elischer.org> Cc: Pawel Jakub Dawidek <pjd@FreeBSD.org>, FreeBSD Current <freebsd-current@FreeBSD.org>, re@FreeBSD.org, Giorgos Keramidas <keramida@FreeBSD.org> Subject: Re: 6.0 VFS/VM over-runs. Was: Apparent strange disk behaviour in 6.0 Message-ID: <20050729144452.GA95803@stack.nl> In-Reply-To: <42E94A88.4010603@elischer.org> References: <42E88135.30603@elischer.org> <42E88F2B.5000108@elischer.org> <20050728082844.GW46538@darkness.comp.waw.pl> <42E898A6.6010803@elischer.org> <20050728115251.GA20091@beatrix.daedalusnetworks.priv> <20050728135613.GD46538@darkness.comp.waw.pl> <42E93EE1.2090009@elischer.org> <42E94310.20806@samsco.org> <42E94A88.4010603@elischer.org>
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On Thu, Jul 28, 2005 at 02:13:44PM -0700, Julian Elischer wrote:
> mount a large partition that has some room.. hopefully several times
> the space of all RAM.
> .
>
> do:
>
> dd if=/dev/zero of=/${mountpoint}/bigfile bs=128k count=1000000 & iostat 1
>
>
> notice that dd dies with "not enough swapspace" after some number of
> seconds.
> (there is no swap attached). also notice that until the crash, IO speed
> was max for the
> disk.
>
> then add swap and do it again.
>
> notice that at teh point where dd previously crashed, the swap disk
> springs into life and disk IO on your main disk goes into the toilet.
> notice that dd gets swapped out. (!!!!)
>
> when the disk recovers enough, dd pages back in and creates more IO but
> in teh mean time there is no IO
> going on to the disk.. (watch the LEDs).
Just to be clear, this happens on 5-STABLE, 6-STABLE and 7-CURRENT.
Marc
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