Newsgroups: comp.arch
Path: utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!snitor!rmc
From: rmc@snitor.UUCP (Russell Crook)
Subject: Re: Memory hierarchy
Message-ID: <1991Apr2.163914.7948@snitor.uucp>
Sender: usenet@snitor.uucp (nntp news poster)
Organization: Siemens Nixdorf Information Systems Ltd.
References: <00670398761@elgamy.RAIDERNET.COM> <-+EAGCE@xds13.ferranti.com> <3306@crdos1.crd.ge.COM>
Date: Tue, 2 Apr 1991 16:39:14 GMT
Lines: 33

From a previous posting... (sorry, my news software bunged up):

  The problem is that the optical disks fall at a funny place in the
  hierarchy. Typically the ration of cache to memory, memory to disk,
  disk to tape is an order of magnitude in size, access time, and
  cost/bit. Optical is not on that path in terms of size or cost, and with
  new larger disks, neither are tapes. There is a real need for a large
  backup medium right now.


Actually, there *is* such a beast (albeit rare and expensive) called
optical (write once) tape.  A company called CREO (in Vancouver)
makes the drive (at something like 250,000$ or so), and a single
tape reel stores several terabytes (I believe).  NASA now has
one, and I think it was shown at last year's CeBit in Hannover.
Transfer rate is somewhere under 1Mbyte/sec., and it takes some
number of days to write a complete tape!  There is a high speed search
mode (the tape is block addressable).

Sorry for the fuzziness in the above numbers... I had some blurbs on it,
but I can't find them at the moment.
------------------------------------------------------------------------------
Russell Crook, Siemens Nixdorf Information Systems, Toronto Development Centre
2235 Sheppard Ave. E., Willowdale, Ontario, Canada M2J 5B5   +1 416 496 8510
uunet!{imax,lsuc,mnetor}!nixtdc!rmc,  rmc%nixtdc.uucp@{eunet.eu,uunet.uu}.net,
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      "... technology so advanced, even we don't know what it does."

-- 
------------------------------------------------------------------------------
Russell Crook, Siemens Nixdorf Information Systems, Toronto Development Centre
2235 Sheppard Ave. E., Willowdale, Ontario, Canada M2J 5B5   +1 416 496 8510
uunet!{imax,lsuc,mnetor}!nixtdc!rmc,  rmc%nixtdc.uucp@{eunet.eu,uunet.uu}.net,