To: Edward Vielmetti 
Cc: Rex Ballard 
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On Sun, 25 Sep 1994, Edward Vielmetti wrote:
> Rex Ballard writes:
>   A 486/66 with 3 1.2 gig SCSI drives and the typical 8 or 16 megabytes of
>   memory along with 256K cache, and 2k internal cache can run about 60 times
>   more efficiently.  Theorically then, you could support about 6000
>   simulaneous users (actually more) in an optimized http/html server and/or
>   a basic SMTP/NNTP server environment.
>   
> In our Online Career Center application, which delivers more than 1,000,000
> targetted employment resources per month, we are running on a 486/50 and
> BSDI.
> 
> Relative to your "theoretical" server support, I would make several 
> observations:
>   - you need more memory (we support full text searches across 
>     tens of megabytes of data)
If you are only going directly after targetted HTML references, there
is less data/scanning involved.  If you were going after full 2 gig
WAIS searches, you would be MUCH more limited in the number of users.
Ideally, you would want to give users a multicast of text data which
they could search and when they reference graphics or follow-ups, they
would then call your http server.
>   - you will be limited in disk i/o by controller performance
Again, this depends on whether you are dealing with full searches of
large databases at your server, or are simply providing supplemental
reference information via your server.
>   - you still need more memory
Obviously, the more memory the better.  A SCSI ram disk as a swap
device would be a real good idea for kilousers.
>   - it's hard to find 6,000 modems (or) 6,000 people on the net at
>     the same time who are all interested in the same thing.
There in lies the key.  You use the net.  That reduces or eliminates
the need for kilomodems.  Second, you can rely on "working time" for
most interactive users.  The average user spends 30 seconds per kilobyte
of text.  Graphics take longer to transfer, but read-ahead and buffering
again make it possible to serve many people very quickly.

I would estimate a more practical limit of about 1,000 users for a Mosaic
application.  It would be more like 400 users for a WAIS server.  You
would probably want to split the WAIS server into a front-end and several
source back-ends.

> thanks
> 
> --Ed
> 
>   Edward Vielmetti, vice president for research, Msen Inc. emv@Msen.com
> Msen Inc., 320 Miller, Ann Arbor MI  48103 +1 313 998 4562 (fax: 998 4563)
> 




From jvncnet!mercury.interpath.net!obstimes Mon Sep 26 19:07:03 1994