if you pay for power, replacing 8 P4s with 1 dual quad-core xeon or opteron usually saves you enough in power costs to pay for the capital cost in a few months.

For me, the big differentiator is robustness and reliability. KVM will get there, I'm sure. But in the hosting space, Xen is the established tool, and KVM is the new technology. Nearly all the linux developers are rooting hard for KVM, which may mean that it will become better. Personally, I'm hedging my bets by learning both. But for now, at least, I think Xen is the best choice for the hosting provider.

I'm pretty sure I've emailed you to ask dumb questions several times, and you answered. :)

Xen and KVM can do similar things, yes, however, last time I evaluated it (which was about a year ago, and things are changing fast) KVM was wholly unsuitable for production use. The stability and performance had a long way to go before it came anywhere near Xen.

On the other hand, KVM is much easier if what you really need is an accelerated qemu to test something real quick. setting up Xen on the desktop is a huge pain in the ass.

From a service provider perspective, all the parts of xen that need to be upstream are upstream. Guest support has been upstream for some time now. I'm fine running a funny Linux kernel (or a funny NetBSD or OpenSolaris kernel) in the dom0.

"The hypervisor is linux" is the idea behind KVM. The Xen hypervisor is most certainly not Linux.

we've got a chaper on running OpenSolaris and NetBSD Dom0s in the book. We got our first taste of Xen, in fact, on NetBSD before moving to Linux Dom0s (we're talking about moving back, now that NetBSD 5 is out with x86_64 and i386PAE support)

not that I have anything against Persig, but xen/zen puns are pretty worn out. We had a bit of a scare when we noticed that the proof for the rear cover said "Xen and the art of virtualization" - I mean, Our "no persig puns" rule aside, that's what the Cambridge folks called one of the first papers on Xen, so there would have been copyright issues. No starch caught the mistake before it hit paper, though.

for a long time... it was a little keychain dongle... you push a sequence on the buttons on front and it lets you see the passwords. There are not that many buttons, so if it's stolen don't expect it to last more than a few days, but it'll slow 'em down hopefully long enough to let you change your passwords.

but mine broke :(

if you are using a browser that is commonly compromised by opening the incorrect webpage, you are a moron. Don't run IE, don't run flash, and run noscript, and you should be fine.

Exactly what I meant. firefox on linux noscript and without flash is fairly safe

computer, my browser is completely broken.

restore from a known good backup whenever the root account is compromised, be it compromised by a worm or a human, in part because it's impossible to tell the difference between a human pretending to be a worm and a worm, so it is quite difficult (perhaps impossible) to know what the attacker did, and how to undo the damage.

1. the money is pretty good, at least for us UNIX janitors. six figures for a guy who never shows up before 11 and barely made it through highschool (that's me) is hard to beat in most fields. (of course, this is Silicon Valley; you're taking a 30% paycut if you are inland.) I don't know of anything outside sales where being self taught (and obviously good) carries as much respect as it does in IT.

2. standards for dress and social skills are low. My uniform consists of a company T shirt (not the same shirt... I have 7 of them, really!) worn jeans, and heavy boots with a heel grounder. I shave once a month and cut my hair less often. People are okay with me saying things like "the vendor is trying to lock you in so they can screw you" (my favorite luke quote is "If you single-source anything, the company you our buying from has a fiduciary duty to their shareholders to screw you.)

3. the white guy bonus (By which I mean, the premium you get for being on site, and a native speaker of the language. It has more to do with accent and the patience to understand accents than anything else.) is giant. When the boss was born in the Philippians and half the tech staff was born in India or China, being willing to say "what?" and repeating back what people have said so that you actually know what the hell is going on means that you can become massively more valuable than average by just being slightly less racist and taking a few minutes to understand what someone is trying to say. Really, dealing with an accent is much less difficult than dealing with a non-technical, in my mind. Besides the funny talking foreigners make lunch time much more interesting. Like the song says, we're all a little bit racist, but if you can keep it in your pants while you are at work, you are ahead of the game. Most people can't.

4. there is room for both gristled experts who have been doing the same thing since the 70s, and neophiles who get bored after three years. Some things are always changing but some things are the same. (I know guys who have been using UNIX like operating systems longer than I have been drawing breath. Their skills are still relevant.)

Personally, I believe *NIX skills to be much more durable, time-wise, than Microsoft skills, simply because you can follow it down to what is actually happening (something that I believe is difficult to do on a windows system.) and while the interfaces change fairly rapidly both in *NIX and Windows, what the system actually does changes very slowly.

5. Outsourcing is more difficult than you think. One place was trying to outsource all their IT. they were trying the first time I worked for them; I left for greener pastures a year later. A year later, I came back and worked for this company again. It wasn't until I had been working for another year before they got an outsourcing firm that was worth anything at all.

you are really into it. You are competing with people who are essentially willing to do it for free, either because we are that into it, or because we lack the interpersonal skills to do anything else (sometimes, a little of both)

That said, it sounds like you have a bigger problem with your bosses than with the IT field. there are places in IT that have good bosses, and it makes all the difference in the world. When I was a youngster, I got a bad boss once, and I, too decided I was leaving IT. I took a month off and a road trip to decide what I wanted to do, but when I was done with that, I got another IT job, one with a decent manager.