Date: Fri, 29 Jul 2005 12:40:31 -0700 From: Julian Elischer <julian@elischer.org> To: Marc Olzheim <marcolz@stack.nl> Cc: re@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org>, Pawel Jakub Dawidek <pjd@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: <42EA862F.70205@elischer.org> In-Reply-To: <20050729144452.GA95803@stack.nl> 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> <20050729144452.GA95803@stack.nl>
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Marc Olzheim wrote:
>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.
>
>
it doesn't appear to hit 5.4. at least not for my small ATA based
workstation.
>Marc
>
>
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