Yikes, I may really have stepped in it with that filesystem check... I first mounted the filesystem, and everything looked fine after replacing sdc1 with sdd1. I then ran fsck -f /dev/md0, and it started to report problems after 10-15 minutes. Here's one of them, they all said the same except for the block number: "Error reading block 5767176 (Attempt to read block from filesystem resulted in short read) while reading inode and block bitmaps. Ignore error<y>?" I just kept pressing y and then approving a forced rewrite, as I thought it was just a few blocks, but after approving 40 or so rewrites, I got cold feet, cancelled fsck, and tried to remount md0 through nautilus. But it wouldn't. Instead, I get this message: Error mounting /dev/md0 at /media/ubuntu/be265e78-0c46-41fb-96ba-fda269e74a60: Command-line `mount -t "ext4" -o "uhelper=udisks2,nodev,nosuid" "/dev/md0" "/media/ubuntu/be265e78-0c46-41fb-96ba-fda269e74a60"' exited with non-zero exit status 32: mount: wrong fs type, bad option, bad superblock on /dev/md0, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so Naturally, I ran dmesg | tail, and got this; [104349.032352] EXT4-fs (md0): can't read group descriptor 378 [104350.997625] EXT4-fs (md0): can't read group descriptor 250 [104739.002433] EXT4-fs (md0): can't read group descriptor 250 [104780.612995] EXT4-fs (md0): can't read group descriptor 250 I then stopped the array, and restarted it, which gave me this message: mdadm: clearing FAULTY flag for device 1 in /dev/md0 for /dev/sdb1 Note that this is not the device that was giving me trouble before, nor is it the on I replaced it with. What have I done wrong here? Nicholas Ipsen -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html