> > > database system, or work on some network protocol.
> > so you mean customer who needs completely own server but in provider's
> > room.
> > 
> > it such case any of new small rack-mount servers do that job excellent
> 
> Yes, and if you need 100 of these "new small rack-mount servers"?
> 
> Or 500?
> 
> How much would it cost to buy, run, and maintain 100 or 500 machines

still less than such mainframe

500*1000 USD=500000USD = price of absolute mainframe minumum

> when a single mainframe would do the same thing?
> 
> Who gets to install 500 hard drives? How often will drives fail?
> How often will other components fail? Answer: often

> How often would a mainframe fail? Answer: almost never

but their elements fail. their disks fail etc.
 
> How long would it take to setup another box for a customer? What if

1-2 minutes.

> you run out of boxes and have to turn away customers? Mainframe is
> the solution.
> -- 
> Kevin P. Neal                                http://www.pobox.com/~kpn/
> 
> "It sounded pretty good, but it's hard to tell how it will work out
> in practice." -- Dennis Ritchie, ~1977, "Summary of a DEC 32-bit machine"
> 

-----------------------------------------------
UNIX *is* user friendly.
It is just a bit selective about his friends.