I have a Western Digital 500GB passport plugged into my Raspberry Pi through a powered hub. The problem is that it seems to lose the connection and unmount every so often with the following dmesg:
[1208317.372126] EXT4-fs error (device sdb1): ext4_find_entry:935: inode #18096148: comm zsh: reading directory lblock 0**
It then automatically remounts as the hard drive is detected again (and it is configured in fstab). I then end up with ugly mounts like this:
/dev/sda1 on /my_passport type ext2 (rw,relatime,user_xattr,barrier=1)
/dev/sdb1 on /my_passport type ext2 (rw,relatime,user_xattr,barrier=1)
/dev/sdc1 on /my_passport type ext2 (rw,relatime,user_xattr,barrier=1)
/dev/sdc1 is in fact the only busy block device.
Thinking it came from the hub, I plugged it into my laptop through the powered hub. Unfortunately, the behavior is not reproducible even with intensive read/write access. I also tried unplugging the hub when it was connected to the laptop to make sure the USB power from the laptop didn't automatically take over. Basically, I am pretty certain that the problem isn't coming from the hub.
What's the problem here? How can I fix it?