The title is a little unfair and Kostadis is doing a good job in his blog explaining a bit more about WAFL and why he feels it is not a file-system.
It's interesting to see where he goes with this, in his first exposition, I was beginning to worry that he was going to claim that it was not a file system because it was missing some operations that a file-system should have; so WAFL is just a partially implemented file-system. And to a certain extent, I think that is the case.
I would like to see some more detail how it is implemented at the OnTap level i.e how does WAFL become a file-system which allows the heads to store files; how a LUN is encapsulated with in WAFL etc.
But it is good to see NetApp beginning to address or at least talk about what people feel is a weakness in their array implementation.
