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.

January 12, 2008 | Filed Under howto, linux, open source, tricks

10 Comments 

10 Responses to “Get More Space Out of Your ext3 Partition”

  1. anon on January 12th, 2008 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.. :)

  2. Thomas Einwaller on January 12th, 2008 4:34 pm

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

  3. fsdaily.com on January 13th, 2008 4:45 am

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  4. Martin Ankerl » Blog Archive » Logical Volume Manager Cheatsheet on February 5th, 2008 12:08 am

    [...] First I create the physical volume on the partition sdg1, create a new volume group ext_vg that contains this physical volumen, and create a new logical volume of size 450GB within thie volume group. Finally create the filesystem (disabled reservation space, see Get More Space Out of Your ext3 Partition). [...]

  5. Nemilar on February 16th, 2008 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!

  6. MistaED on February 16th, 2008 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% :)

  7. Martin Ankerl on February 16th, 2008 9:28 am

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

  8. yang on February 24th, 2008 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..

  9. Martin Ankerl on February 24th, 2008 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

  10. Kunal Gautam on November 1st, 2008 3:06 pm

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

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