How much extra performance are dual processors on a Linux-based system going to give vs. a single processor system? I'm talking about a server running web hosting software (like Plesk or Ensim). Let's say I'm going to put 200 hosting customers on a system with one gig of memory, SCSI hard drives, etc. Say it's a typical mix of customers (the majority are static HTML, some using Perl scripts for guest books and the like, maybe a few running a low-to-medium-traffic bulletin board or similar). Would a dual processor system even be noticeable?

I'm no expert - but we run a mix of dual and single doing what you propose - my understanding is that a dual 1GHZ is no 'faster' than a single - but it can share the load, so for complex sites/servers its good

we use dual for our servers which run freevsd where every customer adds 20 new processes and they don't skip a beat - for our 'straight' hosting we use 866MHZ and 1GHZ and they cope fine with everything

we swapped 100 customers from a Raq3 (which had a 1, 5, 15 min average of 0.36) onto a single 866 and it registers zero most of the day until it rotates the logs and backs up when it goes up to about 0.20

shorty

I have just started building my servers with dual processors. I find that the dual processors are a lot better at handling the sudden spikes that occur. It helps get through those busy periods a lot quicker. Also it is nice to have the extra power for doing backups, etc.

Currently I run Dual PIII 933, 1 gig ram, 18 gig scsi, and they don't have any troubles running 200 clients on a box.

dual is much better with handling the load especially during log crunching :)

yesterday i copied a 425MB mysql backup of my forum from my dual p3 866 to my raq4 and tested it by reimporting the dump file into my raq4 and the load hit 4.25 for 18 1/2 mins! and there is no activity or sites on my raq4 :eek:

on my dual p3 866 an import takes about 1 - 5 mins and load doesn't go over 0.8 - 1.0 and that's with a dozen sites and 90,000 pageviews/day on the server :)

now if you are hosting a few forums and they are do some importing like that a single cpu server would croak it pretty quickly ;)