"defrag will not run on the big drive"

It probably can't handle the number of sectors... it may exceed the old 'limits'...


"(defrag) it is far less of an issue than with Windows file systems"

Well FAT style file systems seemed to mostly work pretty well if the whole file is consecutive - that's the way the file system was 'designed', if that is not insulting the word 'design' (is a 'kludge' a 'design'?)... they also work reasonably if the size is not too big.

UNIX based file systems work on another concept, in which consecutive sectors of the file logically have no physical relationship with needing adjacent physical sectors - I'm not a total expert with 'Linux' file systems, but if they hold to the UNIX file system 'design' that would be the case. UFS also were intended to span a file system across several pieces of HW - thus 'mount points'.

FAT grew out of DOS which grew up on 'kludged' HW & SW with very humble origins, and like Topsy, 'just grew'. It was intended originally to cope with small size disks and a single 'user' running a single 'process' at a time from a single executable file and a couple of data files that were more or less emulations of 'tape drives' - gradually it coped (more or less well) with multiple overlay program segments and multiple open files, even ISAM.

UFS grew out of another world, in which 'a hard disk' was much more than just a simple piece of HW with a spinning disk - there were often special SW algorithms ('elevator' style) in the disk drivers which automatically optimised the access to the relevant disk sectors and sorted the data flow to match up with the head movements. They were also intended from the beginning to cope with multiple simultaneous processes and users and files. They were usually small 'computers' in themselves, running their own dedicated 'operating system' to handle file accesses - I actually have the text code assembly printout somewhere for one such early 'disk operating system' which ran in the 'disk drive' that was implemented on an early "PC" - anyone guess what? ;-) (that'll bring 'em out of the woodwork!)


Now as to running a SW UFS on a FAT based piece of HW... !!!