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:


Filesystem            Size  Used Avail Use% Mounted on
/dev/sdf1             230G  193G   26G  89% /media/disk


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.

  • anon

    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.. :)

  • Thomas Einwaller

    Nice tip! I got some partitions where I could use that too …

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  • Nemilar

    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!

  • MistaED

    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% :)

  • Martin Ankerl

    Hi MistaED, I have updated the blog with a little warning

  • yang

    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..

  • Martin Ankerl

    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:

  • Kunal Gautam

    Stumbled and Faved in my Bookmark . It really helped . Thanks for sharing