Date: Fri, 1 Aug 2003 04:19:51 +0100 From: Bruce Cran <bruce@cran.org.uk> To: soralx@cydem.org.ua Cc: freebsd-hackers@freebsd.org Subject: Re: Ultra ATA card doesn't seem to provide Ultra speeds. Message-ID: <20030801031951.GA33188@buffy.brucec.backnet> In-Reply-To: <200307311833.28209.soralx@cydem.org.ua> References: <200307311455.h6VEtx5i088476@spider.deepcore.dk> <20030731105545.B85113@alpha.yumyumyum.org> <200307311833.28209.soralx@cydem.org.ua>
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On Thu, Jul 31, 2003 at 06:33:28PM -0600, soralx@cydem.org.ua wrote: > > > > Maybe not, but they do give a transferspeed from medium range and that > > > is what can be expected. > > > > Hmm, I guess not everyone does that. We have some seagates here at work we > > were wondering about because they seemed too slow, and we couldn't find > > anything aside from what we already knew... the tranfer speed of the > > SCSI interface, which is basically from drive cache to controller. That is > > unless the manufacturers hide the info somewhere so you really have to > > dig, which wouldnt' surprise me. > > Example took me less than 64 seconds to find (for Seagate Barracuda IV): > http://www.seagate.com/cda/products/discsales/personal/family/0,1085,559,00.html > Look for 'Avg. Sustained Transfer Rate'. AFAIK, every manufacturer I know > gives the sustained transfer rate specs (which are sometime a bit too high than > in reality). If the specs are not specified, it'd be very suspicious, and I > would think 128 time before buying such drives. > The transfer rates are usually given for the outside of the disk I think. Speeds usually drop about 15-20MB/s between the outside and inside. If you've got FreeBSD 5.1, you can use the 'diskinfo -t <disk>' command to measure the performance of the hard drive. It should be a little more accurate than using dd, because I'm guessing the reads/writes don't go through the vfs layer. -- Bruce Cran
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