>>The reliability features of high-end risc boxes are not features of the instruction set.
>>
>>They are, now get into the game.
>
>Are they? I remember learning assembly language for sparc and power when I was
>a student. I don't recall those architectures having instructions relevant to RAS.
>In fact most of the risc ISAs were developed for >workstations and not for "big iron".

I think some of the virtualization features of zArch probably count as ISA. A lot of it has to do with how you handle I/O which some folks don't think is part of the ISA though...but is extremely important no matter what.

>However, it appears to me that the time is coming when commodity x86 will be able
>to scale up far enough to meet almost everyone's needs.

Yup.

>When that happens, I don't
>think so many people will be willing to pay the overhead imposed by architectures
>and instruction sets which have limited production runs and therefore have high
>design costs per unit.

Yup.

>I realize that IBM gets around this issue to a large degree
>by using the same processor design in consoles.

IBM doesn't use the same CPU in consoles and in servers at all. They aren't even really the same ISA really... as the Xbox360 CPU has extra instructions IIRC and CELL is just way different.

They share some elements of the design (circuit technology, etc.).

IBM sets their prices very high, just like every other vendor that has their customers locked in.

>The places I've worked recently, there has always been tremendous resistance to
>that single big box which had a different architecture and OS from all the other
>servers in the place. It was not solely a matter of upfront costs. It was also a
>matter of lock-in, need for different admins to adminster the big box, incompatibility,
>uncertainty about the future of the proprietary platform, >etc.

Heck, IBM gives away hardware some times. A lot like cell phones, if you buy software (a subscription) they will give you the hardware for free!

>Because of those things, I'd have to assume that many places would prefer not to
>use itanium or power if they thought x86 were seriously an option.
>
>It seems possible to me, that once x86 overcomes it scalability problems, it may
>dominate the high end in the same way it dominated PCs, workstations, and low-end servers--and for the same reasons.

That could be.

>I don't think we would return to the days of IBM mainframes, since there are so
>many manufacturers in the world which have licenses to make x86 chips. If we return
>to the days of monopoly, it will be because of the economics of chipmaking, which
>greatly favor larger players, and not because of >intellectual property or lock-in.

I agree that chip economics are the dominant factor. I also sincerely hope we never return to the days of a monopoly manufacturer. HP, IBM, Dell, Sun, etc. would be very foolish to allow that to happen.

DK