Re: Microsoft .NET frontending IBM i

[Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx>]

 On 10/11/2010 1:31 PM, Thorbjoern Ravn Andersen wrote:
> You can get a lot of commodity hardware for that amount of money for
> horizontal scaling....

This conversation is just as scintillating as it has been the 724 other 
times we've had it, and just as theoretical.  I say theoretical because 
I suspect that nobody here is actually running an entire enterprise on 
several dozen sub-$10K servers.

And because it's theoretical, the horizontal folks miss the crucial bit 
every time: how in the heck do you horizontally scale an enterprise 
application?  With commodity systems you're not going to mirror the 
entire application suite on every server.  So, how do you figure out 
which servers run which applications?  How do you upgrade them?  How do 
you fail over?  How do you distribute modifications?

It's EASY to scale a single application horizontally.  A bunch of 
machines knotted up to serve the database, and then the same application 
on every user-facing machine.  It's not a pretty architecture, but it's 
functional.  It's much harder to do it with a heterogeneous suite, 
especially if you mix 3rd party and custom code (God forbid you throw 
open source into the mix).  And it's damned near impossible to provide 
seamless 24/7 redundancy and hot swap with dozens of servers each 
running bits of the corporation.  I'm not saying it can't be done, just 
that it's not as simple as buying another machine from CompUSA and 
flipping the switch.

Yes, with an i you have a single point of failure.  But you also have a 
single point of distribution, access and delivery.  You HA to another 
machine for failover and you're done.

Oof... took me ten minutes to write this.  That's ten minutes of my life 
I'll never get back...

Joe