telnet in to your box and type "df -h". Will tell you whether your hdd is successfully mounted and how much space etc... Results will look like:
Code:Filesystem Size Used Available Use% Mounted on /dev/root 122.0M 64.6M 57.4M 53% / tmpfs 64.0K 12.0K 52.0K 19% /dev /dev/sdb1 54.8G 5.1G 49.7G 9% /media/usb /dev/sda1 1.8T 569.2G 1.3T 31% /media/hdd tmpfs 155.4M 2.3M 153.1M 1% /var/volatile tmpfs 155.4M 0 155.4M 0% /dev/shm