There is a limit for 32-bit setups for RAM, being 4GB, but that's because RAM is talked to and referenced differently to hard disks. I can't give you a definitive and correct explanation as to the why's and how's, because I don't know
At a wild guess, each address in RAM refers to one byte. The limit of 2^32 is 4294967296 bytes, or 4gigabytes total.
On disk, the limit is 2^32 blocks, not bytes. Each of those 2^32 blocks is a good bit bigger than one byte, 4K I think. That's 4294967296 lots of 4kbytes, or ... bucketloads more!. 16192 GB or 16TB, perhaps.
That's the rough explanation, even if the numbers aren't exactly spot on, I think they're about right
dana
