Date: Wed, 14 Nov 2001 17:15:10 -0500 From: Bill Vermillion <bv@wjv.com> To: "Steve O'Hara-Smith" <steve@sohara.org> Cc: damascus@home.com, stable@FreeBSD.ORG Subject: Re: ATA hard drives Message-ID: <20011114171509.A16898@wjv.com> In-Reply-To: <20011114230708.3ceb579d.steve@sohara.org>; from steve@sohara.org on Wed, Nov 14, 2001 at 11:07:08PM %2B0100 References: <bulk.37366.20011114002208@hub.freebsd.org> <bulk.37366.20011114002208@hub.freebsd.org> <20011114051132.A12369@wjv.com> <5.1.0.14.2.20011114091338.03464ec0@netmail.home.com> <20011114095048.A14300@wjv.com> <20011114230708.3ceb579d.steve@sohara.org>
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On Wed, Nov 14, 2001 at 11:07:08PM +0100, Steve O'Hara-Smith thus spoke: > On Wed, 14 Nov 2001 09:50:48 -0500 > Bill Vermillion <bv@wjv.com> wrote: > > Not neccesarily true. About 3-4 years ago I was researching drives > > and found the IBM 5400RPM SCSI drives were faster than the SEAGATE > > Baracudda 7200RPM drives. This was because the IBM's were using a > > new head design. Improved media can also mean that you can write > So the IBMs had a higher capacity or fewer platters at higher > density. Head design alone doesn't help unless it translates to more > bits per inch of track or more tracks per inch or both. That's what head design does - it give you more bits per inch. IBM was using their GMR heads when everyone else was uing MR, both of which IBM had a hand in developing the GMR [Giant MR] had as I recall more of a focused gap because of insulators on both sides of a central pole - and this gave a much narrower magnetic pole - while the standard gap would spread this. > It seems likely that the 160Gb Maxtor 5400 RPM could have a > faster data rate than a 7200 RPM 80Gb unless the Maxtor has rather > more platters than the typical 7200 RPM 80Gb. Disc performance is > a complex thing depending on rotational speed, linear bit density, > track density, head movement speed, head settling time, soft error > rate, pattern of use and probably a few other things. As I recall there is not a wealth of technical data on the Maxtor EIDE drives, but there is on their SCSI drivers. You are correct that disk performance is complex. One of the very important other things you left out is the platter material. With the extremely high track density - last I recall on the big ones was 35,000 tracks/inch you don't have to far to move either. The lightness of the stalks/heads also make things much faster. I've been around magnetic media almost all my life and have become [at times] more familiar with it than I had planned. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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