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From: jones@fortune.UUCP
Newsgroups: comp.arch
Subject: Re: Disk Striping (Really RAMs vs disks)
Message-ID: <394@fortune.UUCP>
Date: Wed, 26-Aug-87 21:06:58 EDT
Article-I.D.: fortune.394
Posted: Wed Aug 26 21:06:58 1987
Date-Received: Sat, 29-Aug-87 06:45:57 EDT
References: <cV=3A8y00UoB0qA0AT@andrew.cmu.edu> <414@astroatc.UUCP> <12718@amdahl.amdahl.com> <420@astroatc.UUCP>
Reply-To: jones@fortune.UUCP (Dan Jones)
Organization: Fortune Systems/SCI Technology Inc., Belmont CA 94002
Lines: 27

In article <420@astroatc.UUCP> johnw@astroatc.UUCP (John F. Wardale) writes:
>Current disk speeds are very close (factor of <=5 ??) to the speeds of
>10 or 20 year old disks.

Actually, in the 5 1/4" disk product world, disk access speeds have
increased by more than a factor of 100 when compared with respect 
to capacity.  And, it doesn't much matter whether you are referring
to track-to-track, average access, or maximum access times.

>As RAMS get larger, it gets more practical to build reasonable
>sized RAM-disks (they may require more volume, and have higher $$/Mbyte 
>
>As I look into my crystal ball, I see RAM and optical (WO) disks
>replacing magnetic memory within 5 years...(say, ~~~  30% of total, 
>and 90% of new systems/designs)
>
I'll take some of that money.  Concerning ram disks, a MByte of DRAM
draws somewhat more than 0.5 amps of +5VDC.  Concerning optical
storage, thermal effects are very slow and, while optomagnetics may
save the day, it has been very slow in coming.  Concerning magnetic
storage, vertical recording alone can increase densities by a factor
of 5.

Dan Jones

'Tis with our judgements as our watches, none
Go just alike, yet each believes his own.	Alexander Pope