Which OS would you choose to run a company's dynamic web application upon if the application was Mod_Perl (with CPAN) and PostgreSQL under Apache? Figure you earn your living from this box!

The official answer that covers it all: it depends.

OK.. you got me... depending on what?

Whenever I've been faced with that decision wheather or not I'm doing this for an biggie corporation that I am directly employed for or making or influencing the decision for a client of mine I take lots of things into consideration. Let's break the problem set up into a couple different issues:

Open Source or Proprietary OS?

In the Real World™ this can be a very thorny issue although as time progresses and Open Source matures a bit this is becoming less of an issue with big companies. Part of the pain here is lots of companies of all sizes want someone "tangible" to be able to put their hands around their necks when things go wrong.

When you have an issue with a Solaris™ box you can call somebody at a help desk and hopefully get some help. This is not the case with Open Source unless you buy support from some commercial concern that sells support for such things. Even then, there is the slowly disappearing perception in the board room that Open Source software is written by a bunch of long hair hippy freak renegade revolutionaries wearing tie dyed shirts, tons of piercings and tattoos.

If you have the fortune of dealing with a client or working for a company that can deal in the Open Source space without reaching for the Malox and/or having nightmares then the decision becomes:

Which Open Source OS do I use?

Here's where some real religous arguments come in. Getting past all that there are some things to consider and rather than lead you to specific OS-es I'll shoot you some bullets here:

• Stability: how long is the reported bug list and are there fixes being released for them?

  This is a two-edged sword no matter how you approach this argument. I know a very brilliant computer scientist that I work with that points out that one OS in particular hardly ever "has to release fixes" for their OS. I got his head spinning one day when I pointed out the release notes for the lastest version of that OS and how many bug-fixes were rolled into it, how many bug reports there had been in the mean time and questioned why didn't they release maintenance releases between versions?

• What is the security stance of this software?

  This is where some research comes in. I can think of one OS I'd rather go with because of how stable their network stack is. You didn't mention it in your list of choices.

• How readily do things port to this OS?

  Of all the OS-es I've ported things to, AIX and Solaris rank at the top of my list for causing me to use salty language while running config and make. OTOH there are a couple of Open Source OS-es at particular release levels that also have caused me some grief as well.

There are probably other things that I'm not thinking of right now that would occur to me while making choices, but nothing is a substitute for doing your own critical analysis and research.

Count Beans!

Another subtopic has to do with the kinds of things that bean counters love to talk about. Return on Investment (ROI), Total Cost of Ownership (TCO) and stuff like that. There are several factors that affect those and a good architect has to take those into consideration as well.

The first is the cost of aquiring the technology in the first place. This includes the cost of the OS itself, the cost of licensing for any application software you need to buy to support the platform, the cost of the hardware, the cost of training for any staff that needs to be trained for this platform (developers, system admins, operators, etc. etc. etc.) and lastly but certainly not leastly is the cost of staff to support it.

IMHO this is where a lot of the Evil Empire's platforms get into trouble OBTW, since I've often noted that it takes quite a few more techies to support one of those platforms than it does to support a *nix platform. And I'm not just saying that because I'm a *nix bigot. I've managed groups that supported both platforms at the same time and know where my staff dollars were going!

After the initial costs of aquiring the platform and bringing it into the house are thought through you also need to consider recurring costs. Annual lisencing and support renewals, staff dollars (again) and lots of soft costs. Here's where you get to look into your crystal ball and consider Mean Time Between Failure (MTBF) numbers and Mean Time To Repair (MTTR) numbers and try and predict what the costs to your business are going to be due to down time.

When I'm selling a solution either into my own corporate environment I actually try and put together a spreadsheet complete with charts and graphs to show the Harvard MBA types (PHBs) and get them to ooh and ahh.. They love that stuff. It's also important to getting your point across and setting expectations. I'll even fudge the numbers across all platforms in the pessimistic direction so that I don't get bit later when things were worse than I thought!

I've probably given you way too much information, but I hope it helps

PS

Don't fall for the obvious trap. Open Source is not zero dollar cost. There are many costs both real and soft involved in any solution wheather it be Open Source or Proprietary.