I could probably dig out my old "speeds and feeds" documents (actually
little laminated cards we gave out to customers and prospects) that listed
the NVS size options of, as I recall, 4M, 8M, 12M, and 16M and some other
stuff. They are probably in the attic. I may have time to do this in the
coming weeks before it gets too hot to forage in the attic. Maybe I will
post a scan of one or more of them.
T. J. Watson . . . yeah -- maybe five computers... I, for one, am glad he
underestimated!
Larry Chenevert
----- Original Message -----
From: "Bill Fairchild" <bi...@mainstar.com>
Newsgroups: bit.listserv.ibm-main
To: <IBM-MAIN@bama.ua.edu>
Sent: Wednesday, May 05, 2010 9:21 AM
Subject: Re: How to analyze a volume's access by dataset
I remember now about Amdahl's CSIM. Thanks for the lengthy post on it.
Cache and NVS sizes were indeed vanishingly small in the 1980s compared to
today's models. I remember attending a SHARE session, ca. 1989, in which
an IBM cache control unit person from Tucson said that IBM had modeled
vast amounts of traced user I/O requests and decided that 4M, or at most
8M, of NVS was all that anyone would ever need to support DASD fast
writes. This reminds of me T. J. Watson's prediction in 1943 that "there
is a world market for maybe five computers." lol
Bill Fairchild
Software Developer
Rocket Software
275 Grove Street * Newton, MA 02466-2272 * USA
Tel: +1.617.614.4503 * Mobile: +1.508.341.1715
Email: bi...@mainstar.com
Web: www.rocketsoftware.com
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On
Behalf Of Larry Chenevert
Sent: Tuesday, May 04, 2010 7:45 PM
To: IBM-MAIN@bama.ua.edu
Subject: Re: How to analyze a volume's access by dataset
For those who were not there at the time -- in the 80's, when cache and
fast-write were first introduced, caches were tiny compared to current
technology, and NVS sizes were even smaller -- much smaller. Memory for
cache and NVS was quite expensive. Caching and fast-write were, for a
short
time, specified on a dataset by dataset basis.
Many internal marketing tools have corners cut in development (well I
guess
some companies even cut corners on their products!) and have very rough
user
interfaces, but not CSIM, which had all the attributes, look and feel of a
flagship product. It was not a product, but was a tool for internal
people
to use -- although it was probably left with some customers.
I suppose this tool could have been used to model the performance of
different cache algorithms but I doubt it was ever used in that mode.
Larry Chenevert
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