Subtitle: Stuff that Microsoft officially says you can do, but you probably shouldn’t.
If you use Win XP or newer, you may use the NTFS file system rather than the older FAT or FAT32. (Of course, NT and Win 2000 also made it available).
NTFS works ok. In fact, it offers some nifty capabilities that the FAT and FAT32 systems did not.
NTFS gives you some real flexibility in how you set up partitions and drives. Rather than re-sizing a partition, you can add another partition and make it look like a folder in the drive that was getting too full. Sounds cool, right? Here’s a way to add capacity without having a zillion drive letters! Well, there are some gotchas.
Trouble is, if you want to move stuff in or out of that folder, it might as well be on another hard drive. Even if the partition you mount to the folder is on the same physical drive, it is treated as if it’s on a different platter. You can tell Windows to MOVE, but it will copy and delete.
So, the original partition can fill up, even though you may have a huge amount of available space in that mounted drive/partition.
Also, Defrag doesn’t seem to even see the files in there. All in all, it is a cool idea but of very limited usefulness. Of course, the real Windows and IT guys already knew that…