Date: Wed, 30 Mar 2005 22:03:32 +0200 From: Martin Nilsson <martin@gneto.com> To: freebsd-current@FreeBSD.org Subject: Re: ciss(4): speed degradation for Compaq Smart Array [edited] Message-ID: <424B0614.5000902@gneto.com> In-Reply-To: <20050330090813.B64732@carver.gumbysoft.com> References: <20050330191824.4c08acc6.aka@veco.ru> <20050330090813.B64732@carver.gumbysoft.com>
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Doug White wrote / skrev: > > I'd also suggest using a tool like iozone to run your tests instead of dd. > Unless your workload consists of entirely sequential writes this perf test > is worthless. What is wrong with using dd to measure max read/write bandwith of the controller-disk system? I use the following to determine if there are any obvious problems with new hardware: (ad1 should not have any useful data). At the same time I run "systat -v 1" on another console. dd if=/dev/zero of=/dev/ad1 bs=128k dd if=/dev/ad1 of=/dev/null bs=128k On a modern disk this should give numbers in the vicinity of 50MB/s at the beginning of the disk. This tells me in seconds if there is something wrong with the controller, cable, disk (or FreeBSD driver). If I can't get decent bandwith with this simple test, how could I get good performance with any other test program? Regards, Martin
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