Just seen a video title about how Linux defeated UNIX™; it is quite hard to dispute this givennd that that Linux is alive, well, and thriving. But I would argue that it isn’t quite true.
First of all, UNIX™ is technically alive as Solaris, HP-UX and AIX are still active. And there may well be rarer versions out there – and I’m excluding operating systems that meet the trademark requirements but aren’t really “Unix” (we could argue all day about what is and what isn’t “Unix”).
But the market for UNIX™ machines is a great deal smaller than it used to be. And why is that? I would argue that whilst Linux made the transition easier, it isn’t the real reason why many organisations swapped out their high-priced machines for cheaper machines.
And that gives a bit of a clue. Whilst the high-priced machines from Sun, SGI, HP, IBM, Digital, etc. weren’t over-priced they were expensive. The hardware was built to be exceptionally reliable – for example some of the Suns I worked with could deal with a processor failure by simply turning off that processor and letting an engineer replace the board all whilst the system was up and running.
No what “killed” those expensive UNIX™ machines was virtualisation and the use of commodity hardware. If a modern server dies, the virtual servers running on it are simply migrated to a working server suffering at worst a reboot (but probably not).
Plus there was a realisation that not everything needed to be continually available.