Get More Space Out of Your ext3 Partition
I have just discovered that ext3 defaults to reserving 5% of its partition exclusively for root, as a precaution measure that your system does not get FUBAR when you use it for your root partition. I have a 230GB external USB disk that I use for all my big storage requirements, downloaded stuff, backups etc. Due to this reservation I had 11.5GB of unusable disk space, thankfully this is easy to fix:
tune2fs -m 0 /dev/sdf1
Replace sdf1 with your partition name. You don’t even have to unmount your disk. Voilá, 11.5 GB more space for free 
Here is the output of df -h as proof:
Before:
Filesystem Size Used Avail Use% Mounted on /dev/sdf1 230G 193G 26G 89% /media/disk
After:
Filesystem Size Used Avail Use% Mounted on /dev/sdf1 230G 193G 38G 84% /media/disk
If you like this, you might also be interested in How to change Ubuntu forced fsck.
Update: The free space limitation is also used to prevent fragmentation. So if you set the limit to zero and operate on a very full harddisk for a while, your filesystem might slow down.
Tags: ext3, harddisk, howto, linux, trick, ubuntu, wastedspace
January 12th, 2008 at 4:28 pm
this is awesome!! i was wondering why the data on my 500 gig drive wouldnt fit back on the same drive once it was changed from ntfs to ext3. mystery solved..
January 12th, 2008 at 4:34 pm
Nice tip! I got some partitions where I could use that too …
February 16th, 2008 at 12:47 am
Very awesome find! I can’t believe I never knew about this. In my particular case, I just reduced the reserved blocks to 3% (-m 3), which gives me a few extra gigs.
Thanks for the post!
February 16th, 2008 at 8:30 am
Yeah I wouldn’t recommend doing this at all. That reserved space is to reduce disk file fragmentation so if you fill it up then your filesystem will be very fragmented if it is always full. Please update your blog saying this so not everyone makes it 0%
February 16th, 2008 at 9:28 am
Hi MistaED, I have updated the blog with a little warning
February 24th, 2008 at 2:45 pm
Where do I paste ‘tune2fs -m 0 /dev/sdf1′? Or what do I do with it, my computer only holds 18.35 gigs X_x so yea..
February 24th, 2008 at 2:51 pm
yang, open e.g. gnome-terminal. But please read something about how the command line works before just copy & pasting commands, this can be dangerous when you do not know what you are doing…
Here is a link: http://www.freesoftwaremagazine.com/articles/command_line_intro