Ubuntu – get more free space than ext4 after formatting in XFS

There are a few things going on here. gparted reports the actual used/free space. The kernel reduces the available count by the reserved space. After you removed the reserved space, the free count did not change because the reserved blocks already were free; it is just that non root users are not allowed to invade that space to prevent them from causing trouble by filling up the disk. The gnome numbers are a little flaky because of a bug. Instead of reporting the used space that the kernel reports ( and df shows ), it computes it by subtracting the free space from the total. This causes it to show reserved space as used.

The missing 4GB is actually used is the fs overhead for ext4. NTFS only initially allocates a small amount of space for the MFT, and grows it as needed. The ext series of filesystems though, allocate space for the inode table ( rough equivalent of the MFT ) at format time and it can not grow. The space missing from the reported total space is the inode table. The remaining bit of used space is from the journal ( usually 128 mb ) and resize inodes.

After some fiddling about, I was able to reclaim a large amount of space with tune2fs:

wim@wim-ubuntu:~/Desktop$ df -h | grep sdc
/dev/sdc1             1.8T  1.7T  352M 100% /media/data
wim@wim-ubuntu:~/Desktop$ sudo tune2fs -l /dev/sdc1 | grep 'Reserved block count'
Reserved block count:     24418900
wim@wim-ubuntu:~/Desktop$ sudo tune2fs -m 0 /dev/sdc1
tune2fs 1.41.14 (22-Dec-2010)
Setting reserved blocks percentage to 0% (0 blocks)
wim@wim-ubuntu:~/Desktop$ sudo tune2fs -l /dev/sdc1 | grep 'Reserved block count'
Reserved block count:     0
wim@wim-ubuntu:~/Desktop$ df -h | grep sdc
/dev/sdc1             1.8T  1.7T   94G  95% /media/data

Apparently linux reserve 5% of new partitions for the root user and system services, so that when you run out of disk space, root can still log in and clean stuff up with system services running ok. Seems kind of bananas to me when the system services only need a hundred meg or so, and 5% of a 2TB drive is a $h17load more than that.. shrugs

This left me with 93.5 GB free, which still leaves about 30 gig unaccounted for, so if anyone has any more ideas feel free to chip in!