[namtih]

At least I don't have such problem you've described and this is something I remember what I did. So it could be worth a try. But if it's the solution, I don't know.
My fstab looks like this. So the line with sda2 could be interesting:

Code:

root@xbian ~ # more /etc/fstab
proc            /proc           proc    defaults        0       0
/dev/mmcblk0p1  /boot           vfat    defaults,noatime,nodiratime,sync          0       0
/dev/sda2       /               ext4    defaults,noatime,nodiratime,async         0       0
UUID=DA205B73205B559B /mnt/hdd  ntfs-3g defaults,noatime,nodiratime,async,big_writes  0   0
/var/swapfile   swap            swap    defaults        0       0

I also disabled the automatic USB mount:

Terminal

nano /etc/usbmount/usbmount.conf
ENABLED=0

The final df looks like this:

Code:

root@xbian ~ # df
Filesystem      1K-blocks       Used Available Use% Mounted on
rootfs            7706072    1427368   6271952  19% /
/dev/root         7706072    1427368   6271952  19% /
devtmpfs           191340          0    191340   0% /dev
tmpfs               38284        336     37948   1% /run
tmpfs                5120          0      5120   0% /run/lock
tmpfs               76560          0     76560   0% /run/shm
/dev/mmcblk0p1      34662      10571     24091  31% /boot
/dev/sdb1      1953503968 1771504566 181999402  91% /mnt/hdd