[Tor3]

Here as well. Because of a customer using AIX, though it'll be phased out (as planned - they went with IBM/AIX because IBM could give them up to 20 years of guaranteed support and maintenance). In the not-so-far past there were also customers with all the well-known *nix platforms, IRIX, Solaris, Tru64, but that was some years ago. AIX is still alive though. Definitely not a bad Unix, and it has some unique features for large scale systems. IBM added a lot of Linux compatibility to AIX over the years, after all they were one of the earlier supporters of Linux. Which means it's relatively easy to develop and test on Linux before moving to the main AIX system.