Re: XP / freeze-drying sessions in OS X
Re: XP / freeze-drying sessions in OS X
- Subject: Re: XP / freeze-drying sessions in OS X
- From: "John C. Randolph" <email@hidden>
- Date: Fri, 6 Jul 2001 17:10:28 -0700
On Friday, July 6, 2001, at 11:16 AM, Ken Tabb wrote:
[snip]
The easy answer to this would be: store the freeze-dried sessions on the
NetInfo server (which you're also using as the user authentication). But
if you have (for argument's sake) 500 users, all of whom use approx
(again for argument's sake) 192Mb of RAM in their average session (I
think a realistic amount for OS X w/Classic and a few apps), then you
have 96,000Mb (i.e. over 90Gb) of server disk needed just to store their
*RAM* (that's not their apps / documents / the server software or system
itself). Yikes that's expensive.
Not really. According to PriceWatch, the street price QTY 1 for a
100Gbyte disk today is $271.
Of course, the scenario we're describing here is still somewhat
sub-optimal, since it supposes that if you and I both are running an
app, that we each have a copy of it in our workspace (in the Smalltalk
sense of the word), rather than sharing it. Putting our workspaces on a
central server is also a problem, since it leads to the hazard of that
server getting swamped.
Suppose instead, that all of the machines on a given network had a
common address space, and routinely copied pages back and forth so that
when I connect to a session, most of it's probably on my machine (since
that's where I last used it), but all of my pages have at least one copy
existing on some other machine on the network.
I recommend that anyone interested in global persistance as an OS
feature have a look at the Extremely Reliable Operating System
(www.eros-os.org.) It's quite thought provoking to consider that an
enormous amount of the code we all write is just to translate between
memory and disk representations of the same data. What happens to our
software designs when memory is *reliable*? IOW, if you put something
in memory, it stays there until you take it down, across power loss, CPU
upgrades, disk replacements, etc.
-jcr
"Scientology is evil; its techniques are evil; its practice is a serious
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adherents are sadly deluded and often mentally ill... --Justice
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