Date: Wed, 12 Jan 2000 16:54:28 -0700 From: "Kenneth D. Merry" <ken@kdm.org> To: Joerg Micheel <joerg@cs.waikato.ac.nz> Cc: sthaug@nethelp.no, grios@ddsecurity.com.br, ohoyer@fbwi.fh-wilhelmshaven.de, freebsd-hardware@FreeBSD.ORG Subject: Re: hardware Message-ID: <20000112165428.A93083@panzer.kdm.org> In-Reply-To: <20000113124314.I5228@cs.waikato.ac.nz>; from joerg@cs.waikato.ac.nz on Thu, Jan 13, 2000 at 12:43:14PM %2B1300 References: <387D0354.63159B8@ddsecurity.com.br> <72218.947717759@verdi.nethelp.no> <20000113124314.I5228@cs.waikato.ac.nz>
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On Thu, Jan 13, 2000 at 12:43:14 +1300, Joerg Micheel wrote: > On Wed, Jan 12, 2000 at 11:55:59PM +0100, sthaug@nethelp.no wrote: > > > So i cannot understand, take a closer look: > > > http://www.seagate.com/cda/products/discsales/marketing/detail/0,1121,43,00.shtml > > > > > > May anyone here explain me this ? > > > > As far as I can see, Seagate's specifications are somewhat conflicting, > > or at the very least unclear. I'm looking at the "Performance" table from > > > > http://www.seagate.com/cda/products/discsales/enterprise/tech/0,1131,43,00.shtml > > > > Yes, it says "External (I/O) Transfer Rate (max) 80 MBytes/sec" - but this > > is worthless since it obviously means transfer from the cache. The number > > which is interesting is *sustained* transfer rate, at the outer and inner > > part of the disk. > > > > (Compare with "Internal Transfer Rate (max) 264 Mbits/sec" - you'd need an > > internal transfer rate of more than 640 Mbits/s to get a sustained 80 MB/s > > from the outer part of the disk.) > > > > Even so, an *average* formatted transfer rate of 22.5 MB/s is rather good! > > FWIW, this is a 3.3-RELEASE system: > > da0: <SEAGATE ST150176LW 0002> Fixed Direct Access SCSI-2 device > da0: 40.000MB/s transfers (20.000MHz, offset 8, 16bit), Tagged Queueing Enabled > da0: 47702MB (97693755 512 byte sectors: 255H 63S/T 6081C) > > 48 [negara] (root) benchmarks/rawio/work # rawio /dev/rda0c > Random read Sequential read Random write Sequential write > ID K/sec /sec K/sec /sec K/sec /sec K/sec /sec > anon 3556.7 220 5227.6 319 > > I can't perform any write tests, this drive is in use. That seems very low. What happens with dd? e.g.: dd if=/dev/rda0c of=/dev/null bs=1m count=4096 At least for sequential reads, I would expect something in the neighborhood of what Seagate claims, and their claim of 22.5MB/sec doesn't seem out of line for a new drive with high media density like that one. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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