[jnevill]

That's my concern though. When you look at other enterprise-sized RDBMS you find tight integration at the "machine" level. Oracle's storage, for instance, uses "Blocks" which are sized based on the block size of the disk they are writing to. This tight integration at such a low level is part of what makes these RDBMS's fast. I would imagine that instead of running on an abstract layer that can be commonly built across many OS's that an RDBMS like Sql Server would be more tightly integrated with the machine they are running on in order to maximize performance and disk space. If so, I would really love to dig through what that means for SQL server.

[telotortium]

Might that not imply that the implementation is relatively little tied to a particular OS? Taking your example, as long as there's a way to get the block size for a disk, there's not much more OS-specific code to deal with -- in particular, adapting your code to the file system doesn't need to be done since the DB will essentially create its own anyway. Similarly, only a few threading primitives need to be used -- the DB isn't going to tie itself heavily to the vagaries of the async IO implementation, which does tend to differ heavily and pervasively between platforms.