The Pitfalls of Mainframe Linux
In another forum, an IT project manager from the financial sector asked what might be the downside to mainframe Linux. Since so many have touted the positive aspects of Linux on System z, in balance, what are the drawbacks? Excellent question!
My answer ...
I come from the "big iron" side, but have been a multi-platform player for decades so have some objectivity. Disadvantages of Linux on the mainframe are few and include:
The first challenge is the bar to entry. Even a low-end System z represents a bigger up-front investment than most laymen can make, so running Linux there is beyond the reach of hobbyists or casual Linux users. When such a user shifts and begins to consider Linux professionally, there is a gap due to lack of exposure; they are unfamiliar with the mainframe port. As hardware goes, System z scales extremely well in both directions, up and down. But the very lowest end of the action is the realm of other hardware. (got hand-held?)
A second negative is lack of sexy graphics. While there are plenty of graphical devices for System z and its predecessors (S/390 and older), the Linux port makes no use of them. You can run X windows applications, as most of us mainframe Linux users do every day. But the physical display for such use is attached elsewhere. This goes hand-in-hand with the lack of warm fuzzy feelings many consumers have about their computers: they can't usually touch and see Linux on System z so they don't get to know it in the same intimate way. Virtual machines help, and z/VM is the most robust virtualization environment, but it still does not fill in this gap of a graphical console for Linux. (Then again, some users have the same problem with virtual machines as with mainframe hardware because of the need to touch, see, feel, ... scratch, sniff.)
But surely the worst thing about Linux on the mainframe is the political baggage of the word "mainframe". When people hear it, they immediately think of green screen applications which they hated in prior experience. Forget the advantage that the hardware can support retro code letting companies defer costly package upgrades or painful package replacements. Never mind that the hardware and traditional operating systems have nothing directly to do with the in-your-face formalities of business. "It's a mainframe and we know that that means." [sigh]
Our friend in the financial world probably expected to hear about dollar costs. Sorry, Charlie. Better fishing elsewhere for that kind of stuff. He did, however, ask an important and uncomfortable question. Now, I do not work for IBM and hold no stock in that company so my opinion is not tainted by personal gain: I can fairly say that the biggest con to mainframe Linux is social. There is also a real boundary for low-end scale down, but it is minor.
Mainframe Linux pitfalls? Few and hard to find.