I have an external hard drive with two partitions: A small FAT32 which is mostly empty and works fine and a large ext4 with tons of data, most of which isn't backed up.

The ext4 is visible, but can't be mounted. I get an "error loading journal" error. The drive is a Western Digital Caviar Blue 500GB. Roughly 30GB of that is FAT32 and the rest is the ext4. The light on the enclosure turns red when reading from the bad partition. It was made by Cavalry.

There wasn't any warning, but coincidentally, I've been thinking lately that I should get two large capacity drives for real backups.

Is there anything that can be done? I'm not even sure I have enough storage to backup everything even if it is redeemable.