[CentOS] df command reports inaccurate results?

Wed Jul 23 12:59:58 UTC 2008
Sean Carolan <scarolan at gmail.com>

Can anyone help make sense of this?  This is an ext3 partition.  It's
only showing 403GB out of 426GB used, but then it says only 632MB
available?  Where'd the extra ~25GB go?

[scarolan at server]$ df -H /disks/vrac5

Filesystem             Size   Used  Avail Use% Mounted on
/dev/sdb2             426GB  403GB  632MB 100% /disks/vrac5