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In my experience, mainframes tend to be used where functional requirements are very slow moving and reliability trumps flexibility. I don't know of any case wh
by lucozade 10y ago
In my experience, mainframes tend to be used where functional requirements are very slow moving and reliability trumps flexibility.
I don't know of any case where a mainframe couldn't, in principle, be replaced by a server farm. However, maintaining a sufficiently reliable and secure server farm is a specialist job too so the benefits aren't always clear cut.
Ease of migration is really down to what the mainframe is doing and for how long. In practice, they tend to be in place for a number of years in hub-type roles e.g. general ledgers, payment systems. That sort of thing. The effect is that extricating them is extremely complex and expensive.
However, these issues aren't really limited to mainframes. We have the same problems with trying to extricate Sparc Solaris applications. We generally want to replace them with Lintel as we use them in most applications. But doing so is horribly complicated as they're embedded in byzantine flows that few understand and the systems often assume a level of hardware reliability that commodity boxes don't have.
- cakes 10y agoSimilarly this is why, in some places, people report having "that old XP machine running <software> in the closet" because <software> is really important to them and they have no path forward (it doesn't support > XP, it's actually too vital - though that seems like an odd reason not to update, etc.). You could replace these things with something newer but the concerns by various parties can outweigh the willingness to fight and you probably don't want to be on the receiving end of "I told you so".
- lucozade 10y agoThe XP factor is another good reason why people stay on mainframes. They tend to be supported forever, or as near as dammit. You don't get that (quite reasonably) with consumer grade software and hardware.
- gadders 10y agoAlso, IBM Z series provide full backward compatibility [1], so you can have new hardware and still run your COBOL program from 1976 with no issues. https://en.wikipedia.org/wiki/IBM_System_z#Architecture https://en.wikipedia.org/wiki/IBM_System_z#Architecture