问题：我使用 mdadm 创建的 RAID 10 阵列中有一个降级的磁盘。我首先移除了该磁盘，并用新磁盘替换了它，但当我重建时，我收到一条错误消息，说它无法检测到磁盘的文件系统。我用 fdisk 意识到磁盘标签是 dos（/dev/sdc），内部分区是 GPT（/dev/sdc1）。我使用了 /dev/sdc。计算机启动正常，因此我决定移除磁盘并在擦除并在其上放置 GPT 表后重试。我这样做了，然后将其重新添加到 raid 阵列中。成功了。阵列花了两天时间恢复磁盘。之后，当我重新启动时，我收到一条错误消息。
我没有备份，希望至少能从中挽救一些数据。我读过这篇文章，我认为如果你两次读取磁盘，元数据可能会导致文件系统损坏。我想挽救它，但如果没有选择，也许有人可以给我一个更好的选择来保存它。
启动时出错：
systemd-fsck[687]: fsck.ext4: Bad magic number in super-block while trying to open /dev/md0
systemd-fsck[687]: /dev/md0:
systemd-fsck[687]: The superblock could nto be read or does not describe a valid ext2/ext3/ext4
systemd-fsck[687]: filesystem. If the device is valid and it really contains an ext2/ext3/ext4
systemd-fsck[687]: filesystem (and not swap or ufs or something else), then the superblock
systemd-fsck[687]: is corrupt, and you might try running e2fsck with an alternate superblock:
systemd-fsck[687]: e2fsck -b 8193 <device>
systemd-fsck[687]: or
systemd-fsck[687]: e2fsck -b 32768 <device>
systemd-fsck[687]: fsck failed with exit status 8.
哦哦。下面是：
kernel: EXT4-fs (md0): VFS: Can't find ext4 filesystem
mount[693]: mount: /media/raid10: wrong fs type, bad option, bad superblock on /dev/md0, missing codepage or helper program, or other error.
systemd[1]: media-raid10.mount: Mount process exited, code=exited status=32
systemd[1]: media-raid10.mount: Failed with result 'exit-code'
systemd[1]: Failed to mount /media/raid10.
我尝试了几种 stackoverflow 解决方案，但其中很多似乎都太具破坏性了。任何挂载尝试都失败了。我没有尝试强制执行任何操作，但 mdadm 似乎输出 ok。我移除了重新添加的磁盘以尝试恢复，但 Ubuntu 仍然拒绝启动。
输出mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Mon Mar 23 (01:06:26)
Rid Level : raid10
Array Size : 19532609536 (18627.75 GiB 20001.39 GB)
Used Dev Size : 9766304768 (9313.87 GiB 10000.70 GB)
Raid Devices : 4
Total Devices : 3
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Fri Sep 18 15:56:34 2020
State : clean, degraded
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devces : 0
Layout : near=2
Chunk Size : 512k
Consistency Policy : bitmap
Name : ubuntu-server:0
UUID : d4c7dc04:6db4b430:66269a3b:44ee5c02
Events : 3501
Number Major Minor RaidDevice State
0 8 0 0 active sync set-A /dev/sda
1 8 16 1 active sync set-B /dev/sdb
2 8 48 2 active sync set-A /dev/sdd
- 0 0 3 removed
cat /proc/mdstat 的输出
Personalities: [raid10] [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4]
md 0: active raid10 sdd[2] sda[0] sdb[1]
19532609536 blocks super 1.2 512k chunks 2 near-copies [4/3] [UUU_]
bitmap: 0/146 pages [0kb], 65536KB chunk
unused devices: <none>
编辑：这是我跑步时得到的dumpe2fs -h -o superblock=8193 /dev/md0; dumpe2fs -h -o superblock=32768 /dev/md0
dumpe2fs 1.44.1 (24-Mar-2018)
dumpe2fs: Bad magic number in super-block while trying to open /dev/md0
Couldn't find valid filesystem superblock
dumpe2fs 1.44.1 (24-Mar-2018)
dumpe2fs: Bad magic number in super-block while trying to open /dev/md0
Couldn't find valid filesystem superblock