Date: Tue, 15 Jan 2013 17:45:54 -0500 From: Karim Fodil-Lemelin <fodillemlinkarim@gmail.com> To: freebsd-hackers@freebsd.org Subject: Re: IBM blade server abysmal disk write performances Message-ID: <50F5DC22.6040405@gmail.com> In-Reply-To: <alpine.BSF.2.00.1301152251530.2950@wojtek.tensor.gdynia.pl> References: <CAA3ZYrACHLU-4OyhLdD%2BmfCDR_kubBg-AiVcopL-skqDurE7YA@mail.gmail.com> <50F5BC08.1060700@gmail.com> <alpine.BSF.2.00.1301152251530.2950@wojtek.tensor.gdynia.pl>
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On 15/01/2013 4:54 PM, Wojciech Puchar wrote: >> >> # dd if=/dev/zero of=foo count=1 bs=10240000 >> 1+0 records in >> 1+0 records out >> 10240000 bytes transferred in 19.579077 secs (523007 bytes/sec) >> > you write to file not device, so it will be clustered anyway by FreeBSD. > > 128kB by default, more if you put options MAXPHYS=... in kernel config > and recompile. > > Even with hard drive write cache disabled, it should about one write > per revolution but seems to do 4 writes per second. > > so probably it is not that but much worse failure. > > Did you rest read speed? > > dd if=/dev/disk of=/dev/null bs=512 > > dd if=/dev/disk of=/dev/null bs=4k > > dd if=/dev/disk of=/dev/null bs=128k > As you mentioned the dd file tests were done UFS and not on raw device. I will get those numbers for you. Thanks, Karim.
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