yeah there 2 limitation for size:
*must conform with INT 13H specificaition
*must conform to limitation imposed for FAT16 for dos application.
most hdd images maker/converter sometimes ignore the INT 13H spec:
- can't have more than 63 sectors per cylinder
- can't have more than 1024 cylinders per head
- can't have more than 255 (256?) heads
ignoring the INT 13H spec will make said HDD images behaves wrongly under dosbox.
if mounting the hdd image to specific drive letter, the hdd image must contain just 1 partition only.