我最近安装的 ubuntu 16.04 系统运行不正常（无法启动）。我确实使用 fdisk 检查了硬盘驱动器的状态，发现备份 GPT 表不知何故已损坏。
ubuntu@ubuntu:~$ sudo fdisk -lu /dev/sda
The backup GPT table is corrupt, but the primary appears OK, so that will be used.
Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 574A30DA-2F2E-414A-A537-2E3E2B4F46FA
Device Start End Sectors Size Type
/dev/sda1 4096 611463167 611459072 291.6G Linux …