tune2fs: Free Space in a Storage Partition
The ext2, 3, and 4 filesystems by default all reserve 5% of their capacity for the root user. While this is very important for partitions that contain /var or / (the root of the operating system), it can be a waste of space in drives that are only used for file storage. After making a ext4 partition I realized that I didn’t change the default setting. Instead of having 3.6TB of usable free space on my new hard drive I only had 3.4TB. After a quick google search I found an Ubuntu forum posting with a similar issue: http://ubuntuforums.org/archive/index.php/t-215177.html
The command I used is very simple:
# tune2fs -m 0 /dev/md0
Where /dev/md0 is the partition you are configuring. For more help check out the manual page for tune2fs (# man tune2fs )