Date: Mon, 8 Sep 1997 01:32:27 -0400 From: Lee Cremeans <lee@wakky.dyn.ml.org> To: Simon Shapiro <Shimon@i-Connect.Net> Cc: chat@freebsd.org Subject: Re: lousy disk perf. under cpu load (was IDE vs SCSI) Message-ID: <19970908013227.32344@wakky.dyn.ml.org> In-Reply-To: <XFMail.970907214856.Shimon@i-Connect.Net>; from Simon Shapiro on Sun, Sep 07, 1997 at 09:48:56PM -0700 References: <19970907171110.27847@lemis.com> <XFMail.970907214856.Shimon@i-Connect.Net>
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On Sun, Sep 07, 1997 at 09:48:56PM -0700, Simon Shapiro wrote: > > Hi Greg Lehey; On 07-Sep-97 you wrote: > > .... > > > Well, I can't remember the performance of the mid-70s, but my > > recollection of the performance in the early 80s on, say, a 3330 clone > > was that these drives had 30 sectors (2 spares) per track, and they > > ran at 3600 rpm. Since they weren't buffered, that gives a maximum > > data transfer to the channel of about 860 kB/s. Average positioning > > was round the 30 to 35 ms mark. > > Check out Priam 14" 60MB drives, check Floppy drives from the early 80's. > They were all much faster than that. I clearly remember my Heathkit H8 > seeking at 5-7ms on a 5.25" floppy. Well, Greg mentioned *average* seek...what the floppy-drive manuals list is track-to-track seek. The only drives I remember having anything close to a 30 ms track-to-track were the old stepper-motor PC hard drives of the early 80s, and they were usually 15-20 ms. (They also had 65-85 ms average seek times...yuck.) Also, most floppies still have a track-to-track seek of 5-7 ms...they havent changed much in design since the 80s. For reference, most modern drives have average seek times of around 10ms, and track-to-track seek times of 800us-2ms. PS: When did the first voice-coil-seek hard drives come out? This is a question that's been bugging me for some time now... -- Lee C. -- Manassas, VA, USA (WakkyMouse on DALnet #watertower) A! JW223 YWD++^i WK+++r P&B++ SL++^i GDF B&M KK--i MD+++i P++ I++++ Did $++ E5/10/70/3c/73ac Ee34/1/36 H2 PonPippi Ay77 M | hcremean (at) vt.edu FreeBSD/Linux/Unix hacker...Win95 and M$ evil! (go see www.freebsd.org) My home page: http://wakky.dyn.ml.org/~lee | finger me for geek code
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