I have been using a raspberry PI since more than one year, with two USB 500GB IDE hard drives as a NAS/torrent box. Yesterday, one of the two hard drives started a repetitive rattling noise, and I could not read data from it through sftp.
I assumed it was broken, so I opened the box the raspberry and the hard drives were in, connected the first HD to my laptop using the IDE to USB adapter I had. Windows wasn't able to mount it. I really cannot remember which FS this HD is using, so I tried to mount it on a Debian Virtual Machine. The image below shows the error I get. I have no idea what it means, what I understand is that Debian does not recognize which FS the hard disk is using.

This is the result of fdisk -l (only the part regarding the mentioned HDD):
Disk /dev/sdb: 500.1 GB, 500107862016 bytes 81 heads, 63 sectors/track, 191411 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x17e817e7 Device Boot Start End Blocks Id System /dev/sdb1 2048 976773167 488385560 83 Linux