The point of a parallel file system is that you do not need RAID.
Really? Why has virtually every production parallel file system implementation I've ever seen (using GPFS, Lustre, and PVFS) been done on top of hardware RAID controllers?
One area where I disagree with TFA is the claimed paucity of programming models and tools. Virtually every OS out there supports some kind of concurrent programming model, and often more than one depending on what language is used -- pthreads, Win32 threads, Java threads, OpenMP, MPI or Global Arrays on the high end, etc. Most debuggers (even gdb) also support debugging threaded programs, and if those don't have enough heft, there's always Totalview. The problem is that most ISVs have studiously avoided using any of these except when given no other choice.
No one uses Linux for anything important.
Other than every supercomputer on the planet worth talking about, that is...
Why always nuclear explosions simulation is the primary use for this type of computer?
Uh, because it's paid for out of the NNSA budget?
Sigmund Freud is alleged to have said that in the last analysis the entire field of psychology may reduce to biological electrochemistry.