The most general practice is to save on CPU and spend on RAM. Typical
web applications choke when it comes to I/O and going out to disk;
rarely will your CPU be fully utilized on a load-balanced farm
(considering you're not doing image manipulation or any other
intensive tasks that _could_ be a feature within your app).
RAM size depends on what you cache, and how much of it you cache. If
you're just caching a database for a relatively moderate sized
application you could be surprised how far just a single gig of RAM
will go as far as caching...
As far as where you should fire up Memcached instances, I believe
someone more experienced can answer this (Brad, Steve, Moon,
dormando)? I don't think it should be a problem firing instances on
your WWW servers... you can start out doing that, then do some testing
to see whether it's beneficial to cache to dedicated boxes.
Brian Brooks
[EMAIL PROTECTED]
Mobile: 303.319.8663
On Jan 31, 2008, at 11:44 AM, Karoly Negyesi wrote:
Hi,
I am running a fairly typical web app (Drupal based) on a LAMP stack
and I am about to buy new servers. What's better, putting heaps of RAM
into each frontend (say, 8GB) and caching locally or have separate
boxes which only run memcached ? I plan quad core CPUs (Xeon 5405 or
so) for the web frontends, but even dual quad cores are not out of
question. If you guys say that go for separate boxes, what kind of CPU
power do I need to plan on?
Regards,
NK
