HDD mirror itself?

I was told by a friend that the hard drive, when less than half full, mirrors itself onto the empty space. As soon as that space is needed, it stops the mirror and performance levels drop. I have personally never heard of this. What about you guys?

Drives themselves dont do that no. There are programs you can get which will take an image of your drive and save it so you can roll back to that image in the event of a crash. Dell and Gateway machines come with that ability.

XP Also has this ability called System Restore. If you go to your Control Panel then Sytem, you should have a System Restore tab. This basically takes snapshots of your system at certain intervals and in the event of a crash due to software or the OS you can go back to one of those snapshots to get a working system.

i didnt think there was anything like it either. thanks.