Ext3 Filesystem Missing Some Space, Where Did It Go?

milkyspit · 12-23-2009, 06:41 PM

Hi folks, I'm a forum veteran elsewhere but this is my first post on LQ!

Let me ask if someone could explain something that's puzzled me for a long time. I've got an ext3 volume on my home fileserver that reports numbers under "df -hT" which don't add up. For example...

Code:

Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/sda1     ext3    912G  398G  468G  46% /

According to df, this volume has a total size of 912GB, which should correspond to the sum of used and available space. But 398GB + 468GB = 866GB.

Where did the other 46GB go? That's a heck of a lot of space to go missing for no apparent reason!

syg00 · 12-23-2009, 07:06 PM

This must get asked every week. Ext3 reserves 5% (default) so root can login and fix things when the partition goes full. See the manpage on mkfs.ext3.
For non root (as in /) filesystems can safely be set to zero.

AwesomeMachine · 12-23-2009, 08:12 PM

I would say it's due also to ext3 file system construction. Ext3 is the least space efficient file system.