[LUNI] Disk full, but not really

[Branko Kotur]

I've noticed that when the hard drive starts filling up, about 10% is left in 
reserve so that regular users can't use it.  In other words, take the 
following df output for example:

Filesystem            Size  Used Avail Use% Mounted on
/dev/hda2             9.9G  4.2G  5.3G  44% /
/dev/hda1             145M   19M  119M  14% /boot
/dev/hda6              61G   52G  6.2G  90% /home
/dev/hda5            1012M   38M  923M   4% /tmp

/home obviously isn't full, but since it's at 90%, the user is not able to add 
new files.  Only root can.  Is there a way to disable this behavior?  I 
realize this isn't smart if the drive isn't partitioned, but since the /home 
is on a seperate partition, I don't see any danger at this point.  Quotas are 
enabled, but I've never played with them very much, so I don't know if 
they're what's causing this.

Does linux do this by default or did some software on the server implement 
this?