Well, as noted above, there were two physically failed disks—one which triggered the rebuild, and a second disk which failed with read errors during the rebuild

Well, as noted above, there were two physically failed disks—one which triggered the rebuild, and a second disk which failed with read errors during the rebuild. Then the RAID card died. According to the official policy, the equipment should have been replaced almost five years earlier. So this recovery involved physical recovery of at least one disk to meet the RAID's minimum threshold, then a logical recovery.