Would there be any advantages of using a mainframe instead of a server farm?
I have never used one, does anyone envisions any problems once linux is running?
I found a bit about the subject in mainframes as webservers inSlashdot
For development, and maybe for rapidly adding new 'servers' if you havs a 'one server per customer' environent, creating extra virtual linux machines would also be very handy, I suspect.
You'll quite probably be the first person in the universe to port AOLserver to Linux/S390, as well as trying out OpenACS there. Sounds like a lot of fun Make sure you post the results of your experiment here!
The only possible 'problem' I can think of would be that you're running a newer Linux port, will need to recompile some software on that new platform, and there are less people with experience of Linux/S390 than Linux/x86 you will be able to rely on for help.
In re: to your questions, there are a number of power & cost reasons to use a mainframe rather than a PC farm, but if you're dependent on some i386 closed-source stuff, you don't have that option. And of course, the hardware is absurdly stable (even after 20 years, I should point out. Though by that time you'll wish it wasn't.).
I've been trying to get some time on that shared IBM machine for a couple months now. I have an unhealthy interest in what AOLserver, on a mainframe, could do on the SpecWeb99. If you get the chance, show us some numbers!
The mainframe is a self-contained processing center, powerful enough to process the largest and most diverse workloads in one secure “footprint.” The mainframe is also just as effective when implemented as the primary server in a corporation’s distributed server farm.