Date: Tue, 15 Jan 2013 19:15:10 +0100 (CET) From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> To: Tim Kientzle <tim@kientzle.com> Cc: Karim Fodil-Lemelin <fodillemlinkarim@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: IBM blade server abysmal disk write performances Message-ID: <alpine.BSF.2.00.1301151914080.2295@wojtek.tensor.gdynia.pl> In-Reply-To: <710B89CC-004B-4766-A7C1-0B8CE45F64CF@kientzle.com> References: <50F563BE.7010609@gmail.com> <710B89CC-004B-4766-A7C1-0B8CE45F64CF@kientzle.com>
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>> >> 10000+0 records in >> 10000+0 records out >> 5120000 bytes transferred in 60.024997 secs (85298 bytes/sec) > > What exactly was the 'dd' command you used? > > In particular, what block size did you specify? 5120000/10000=512 default if it takes one revolution for one write it means that write caching is disabled. that's all. linux always uses buffered devices, only relatively recently special OPTION was added to have raw ones. Complete nonsense but it's linux.
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