Blade servers are not fundamentally any different than 1U rackmounts
or any other form factor of server. Blades are smaller, sexier, and
generally overpriced unless you really need their higher rack density.
Mark, you need a much more detailed idea about what it is you're
application is trying to do. (And you didn't even mention disk IO,
which for an RDBMS can be the limiting factor.) As Jun
pointed out, serving 100 requests per second could be nearly trivial,
or very difficult, it all depends on what those requests are doing.
You posted this in the .LRN forum so perhaps you intend to run .LRN?
Modern CPUs, RAM, disks, and networks are so fast that many
interesting sites can be run with quite modest hardware. But even
much fancier hardware isn't all that expensive nowadays. For more
towards the large high-volume end of things, see the Denis Roy's
posts with details on the hardware they use for aiesec.net.
I may be a bit out of date, but currently I'd guess that a rather
high-end dual SMP system might have two 3+ GHz Intel Xeons (or AMD
Athlon MPs or Opterons of similar or better performance), 8+ GB ECC
RAM of commensurate speed, and depending on use, 4-12 or more fast
disks in a RAID array (more disks is better). I'm not sure what that
machine would cost currently but you're not talking tens of
thousands of dollars here. Maybe there are some OpenACS sites out
there big and complicated enough that a monster dual CPU box like that
would be just too wimpy to run the RDBMS, but if there are I haven't
personally heard of any of them.
Most sites probably never need hardware anywhere near that. (For
example, openacs.org certainly runs on much more modest
hardware!) And anyway, if you think you need more than that, my guess
is you're probably either Yahoo or AOL or some big corporate entity
like that with a massive public website, or (more likely) you have
egregiously poorly performing software and just throwing more hardware
at it probably isn't a good idea anyway.
Hardware gets faster all the time, but the design of your software is
still, and probably always will be, the dominant factor in meeting
your performance goals for a large and complex site. If nothing else,
Feb. 2000 slides
on the AOL Digital City site architecture should help show that.