Re: IBM's storage "strategy" was to turn SW products into HW
"That custom-made hardware has firmware /.../ It can fail just like any other software."
Yes, it can fail, and does. In its own little tincan. Where it probably cannot bring the whole house down.
Separation of functions, or shall we say 'sandboxing', is important. Packet storms against the external I/O ports should not be able to crash the main code, especially not all instances at once. Invalid pointer in the main code should not be able to overwrite the data cache. Yet both of these examples are real. And hard to avoid completely in the flat memory model.
So it is quite wrong to claim that *any* storage system is just two servers + software. Like Storagebod did in a cocksure way ("Shark is, and was, simply a pair of RS/6000 or pSeries boxes"), and obnoxiousGit in a more cautious manner ("that's true of every manufacturers storage arrays"). No, it is not true for Shark, nor is it true for Symmetrix. Do not belittle those ancient behemoths, please.