tune2fs -m "reserved space?"

[Justin Conover <justin conover gmail com>]

tune2fs 
-m reserved-blocks-percentage
-r reserved-blocks-count

If what I have read is correct, -m by default uses 5% of the disk space
for "reserved root use"  On my server at home with a /home of 1TB
thats about 50GB of wasted space.

Is this reserved space actually used by ANYTHING?  Like LVM, some kind of fragmentation?

Thanks