Drives can map a logical configuration onto a physical disk.
Files were identified by 12 character names and a user program did not need to know which physical disk was being used for a file.
The disc image can then be tested after it is assembled but before writing to a physical disk.
Remember that a good rule of thumb is to equally split virtual memory between the physical hard disks you have.
You could partition the drive, but you're better off with separate physical disks.
The file must first be moved to a larger physical disk or partition.
Thus, instead of one big hard drive I now have two little ones using the same physical disk.
With a logical volume manager it is possible to grow partitions, even beyond the size of one physical disk.
If the physical disk is healthy, you can subsequently re-add it to the pool.
These conditions made it profitable to sell games and applications via physical disks.