... first case:
Code:
# df -Th
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/sda1     vfat    965M  963M  1.2M 100% /mnt-system
tmpfs        tmpfs    2.0G     0  2.0G   0% /ramdisk
/dev/cloop iso9660    1.9G  1.9G     0 100% /KNOPPIX
/dev/loop0    ext2    257M  3.6M  254M   2% /KNOPPIX-DATA
unionfs       aufs    257M  3.6M  254M   2% /UNIONFS
unionfs       aufs    257M  3.6M  254M   2% /home
tmpfs        tmpfs     10M   68K   10M   1% /UNIONFS/var/run
tmpfs        tmpfs     10M     0   10M   0% /UNIONFS/var/lock
tmpfs        tmpfs    100M   48K  100M   1% /UNIONFS/var/log
tmpfs        tmpfs    2.0G  8.0K  2.0G   1% /tmp
udev         tmpfs     20M  356K   20M   2% /dev
tmpfs        tmpfs    2.0G  4.0K  2.0G   1% /dev/shm
/dev/sdb1     ext4    7.4G  5.9G  1.1G  85% /media/sdb1
second case:
Code:
# df -Th
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/sdb1     vfat    965M  963M  1.2M 100% /mnt-system
tmpfs        tmpfs    2.0G     0  2.0G   0% /ramdisk
/dev/cloop iso9660    1.9G  1.9G     0 100% /KNOPPIX
/dev/loop0    ext2    257M  4.8M  252M   2% /KNOPPIX-DATA
unionfs       aufs    257M  4.8M  252M   2% /UNIONFS
unionfs       aufs    257M  4.8M  252M   2% /home
tmpfs        tmpfs     10M   68K   10M   1% /UNIONFS/var/run
tmpfs        tmpfs     10M     0   10M   0% /UNIONFS/var/lock
tmpfs        tmpfs    100M   48K  100M   1% /UNIONFS/var/log
tmpfs        tmpfs    2.0G  8.0K  2.0G   1% /tmp
udev         tmpfs     20M  356K   20M   2% /dev
tmpfs        tmpfs    2.0G  4.0K  2.0G   1% /dev/shm
/dev/sda1     ext4    7.4G  5.9G  1.1G  85% /media/sda1
If I have a look at init-script I can not find any line which could explain the curious behavior of Knoppix USB-Stick you told us.

Greetings Werner * http://www.wp-schulz.de/knoppix/summary.html
"Build personal Recovery-CD with Knoppix (Knoppix remaster)"