This one came in handy when I bought a 1TB hard drive last week. Most linux distributions reserve 5% of new partitions for the root user and system services. The idea here is even when you run out of disk space, the root user should still be able to log in and system services should still run… this won’t happen if there is no space on the root partition. This policy may have been appropriate in the 90s when hard disk capacities were relatively low but this is 2010 and one can get a 1TB hard drive for a couple of hundred Ghana Cedis. 5% of that is about 51GB and those system services need only a couple of hundred megabytes.
So I decided to reclaim all that disk real estate with this command:
sudo tune2fs -m 0 /dev/sdb1
This sets the reserved blocks to 0%. This is an additional storage drive, I have no need to reserve disk space for system services. You can verify that this actually worked with:
sudo tune2fs -l /dev/sdb1 | grep ‘Reserved block count’
As usual, modify /dev/sdb1 to suit your partition setup. Have fun.