I've found that the best way to repair disk issues (like when the power goes out and a disk gets borked) is to boot into Ubuntu Live Desktop, use "Try Ubuntu", and run an `sudo fsck -y /dev/mapper/<lv partition>`. It forces yes on every prompt - let's be honest, when would you say no to "Inode <random number> appears to have garbage, clear?" - and seems to work fine. Ubuntu Server installers and gparted are just too fiddly.