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From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga
Subject: Re: Cheap disk drives
Message-ID: <33847@sun.uucp>
Date: Fri, 13-Nov-87 13:04:46 EST
Article-I.D.: sun.33847
Posted: Fri Nov 13 13:04:46 1987
Date-Received: Sun, 15-Nov-87 10:30:15 EST
References: <73@mithras> <303@uscacsc.UUCP> <186@dalcsug.UUCP> <1367@squeaker.munsell.UUCP>
Sender: news@sun.uucp
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 23
Keywords: IBM Cheap

In article <1367@squeaker.munsell.UUCP> (Kevin McBride) writes:
>Access time (like 65 milliseconds (ms) and 35 ms) is the time it takes to
>move the head from track to track.  Another spec. that is important is
>the transfer rate (i.e. how fast data goes to and comes from the drive.)

Actually, the second most common spec quoted for hard disks (after capacity)
is 'Average Access Time'. This is the average time it takes for the heads
to go from where you are, to where you want to be. Seagate drives are pigs
and have access times of 85 milleseconds, Maxtor drives are much quicker
and have access times in the range of 18 - 28 milleseconds. This is related
to the track to track time (usually in the microseconds) however voice coil
drives always whip the pants of stepper motor type drives. 

Why do you care? Because AmigaDOS tends to fragment the drive with the
directory in the middle tracks and the data in the outer tracks. The
disk heads end up going from here to there quite a bit. The smaller the
average access time the faster the disk files are found/read. As of this
writing that can be overwhelmed by AmigaDOS overhead, however Andy F. has
told us that will be changing.

--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.