Roy, Thanks, one of the drives does have a badblocks list (/dev/sdc). It is also the only one with reallocated sectors (56 of them). No drives have a non-zero 'Current_Pending_Sector'. This would explain why the rebuild worked for a while, but not now. It doesn't explain whatever was happening to make drives drop out of the array, but I'll resolve the rebuild issue before digging into that. I want to understand what is failing here before I put the drives back into use. I may leave the drive with reallocated sectors out when I reuse the drives. The MD array has a ZFS volume on it (meaning it should get checksum errors if there are problems), and doesn't have critical data, so I followed your instructions on how to disable the BBL and restarted the rebuild. I'll see if it completes now. Joe
