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From: sl@van-bc.UUCP (Stuart Lynne)
Newsgroups: comp.unix.i386
Subject: Re: mkfs gap option
Message-ID: <369@van-bc.UUCP>
Date: 3 May 90 01:38:14 GMT
References: <511590@nstar.UUCP< <1990Apr19.025739.19180@nebulus.UUCP> <PCG.90Apr28151407@rupert.cs.aber.ac.uk> <1990Apr29.000503.10934@nebulus.UUCP> <PCG.90Apr30221039@odin.cs.aber.ac.uk> <715@bilver.UUCP>
Reply-To: sl@van-bc.UUCP (Stuart Lynne)
Organization: Wimsey Associates
Lines: 24

In article <715@bilver.UUCP> bill@bilver.UUCP (Bill Vermillion) writes:
>In article <PCG.90Apr30221039@odin.cs.aber.ac.uk< pcg@cs.aber.ac.uk (Piercarlo Grandi) writes:
><
><   >(virtually a constant), and on interrupt latency and IO operation
><    ^^^^^^^^^^^^^^^^^^^^^^ What is this? Different drives have DIFFERENT
><Bah. Virtually every drive around does 3600 RPM, for an average
><rotational latency of 8.3 ms. Exceptions I know are the optical drives

>And just last week I was looking over the specs on the current Shugart lines,
>and there were 3 different drive rotational speeds listed.

>All were SCSI drives.  Since we just talk to the host in SCSI land it really

Yes, with SCSI the drive manufacturers can finally break loose of the drive
speed. With the ST506/ST412 interface MFM/RLL drives the rotation speed is
fixed at 3600. When you go to SCSI the interface merely specifies that you
can read and write blocks in a range (ie read block m from a range from 0 to
n). So the manufacturer can do anything he wants to give you the n blocks.
From speeding up the rotation or slowing it down or eliminating it entirely
(eg with a RAM disk). It's common on SCSI drives to slow the disk down at
the outside of the disk to take advantage of the extra capacity.

-- 
Stuart.Lynne@wimsey.bc.ca ubc-cs!van-bc!sl 604-937-7532(voice) 604-939-4768(fax)