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.


fantastic !
thank u man
By: Abdulrhman on February 21, 2010
at 10:46 am
Nice..
Thanks!
By: Greatest on June 3, 2010
at 3:33 am
OH YEAH, u just gave me back 370Gb of my 8Tb RAID. Thank You!!!
By: Faxedhead on July 26, 2010
at 9:13 am
Got an extra 200GB back on my home partition!
By: Cr0t on April 17, 2011
at 4:28 pm
Hi – would it be any different for trying to reclaim the 5% of a drive that is NOT where the OS sits? I installed a 1TB drive and only 870GB are free to use. I did ‘sudo tune2fs -m 0 /media/media-1′ (media-1 being the name of the drive) and I got back ‘tune2fs: is a directory while trying to open /media/media-1 Couldn’t find valid filesystem superblock’
Thanks for any help!
By: Brian McCabe on May 15, 2011
at 2:32 pm
Brian, you need to give tune2fs the block device behind your filesystem, not the mount point.
run #mount without any arguments to find out which block device you must use.
By: brain on June 4, 2011
at 4:10 pm
Thank you! It helped me with my new hard driver
Why isn’t this reserve space is not different by default?
e.g. If the HD is bigger than 100 GB, then reserve 500 MB, or only 1%, or something like this?
By: sibannac on July 28, 2011
at 10:20 pm