无法将 grub 安装到 RAID1 (md0)

Question

我的 Ubuntu 12.04 LTS 上有一个 RAID1 阵列，几天前我的 /sda HDD 已更换。我用这个命令来替换：

# go to superuser
sudo bash
# see RAID state
mdadm -Q -D /dev/md0
# State should be "clean, degraded"
# remove broken disk from RAID
mdadm /dev/md0 --fail /dev/sda1
mdadm /dev/md0 --remove /dev/sda1
# see partitions
fdisk -l
# shutdown computer
shutdown now
# physically replace old disk by new
# start system again
# see partitions
fdisk -l
# copy partitions from sdb to sda
sfdisk -d /dev/sdb | sfdisk /dev/sda
# recreate id for sda
sfdisk --change-id /dev/sda 1 fd
# add sda1 to RAID
mdadm /dev/md0 --add /dev/sda1
# see RAID state
mdadm -Q -D /dev/md0
# State should be "clean, degraded, recovering"
# to see status you can use
cat /proc/mdstat

这是同步后我的 mdadm 输出：

/dev/md0:
        Version : 0.90
  Creation Time : Wed Feb 17 16:18:25 2010
     Raid Level : raid1
     Array Size : 470455360 (448.66 GiB 481.75 GB)
  Used Dev Size : 470455360 (448.66 GiB 481.75 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Thu Nov  1 15:19:31 2012
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : 92e6ff4e:ed3ab4bf:fee5eb6c:d9b9cb11
         Events : 0.11049560

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1

构建完成后“fdisk -l”表示我没有有效的分区表/dev/md0。这是我的 fdisk -l 输出：

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 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
Disk identifier: 0x00057d19

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63   940910984   470455461   fd  Linux raid autodetect
/dev/sda2       940910985   976768064    17928540    5  Extended
/dev/sda5       940911048   976768064    17928508+  82  Linux swap / Solaris

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 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
Disk identifier: 0x000667ca

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *          63   940910984   470455461   fd  Linux raid autodetect
/dev/sdb2       940910985   976768064    17928540    5  Extended
/dev/sdb5       940911048   976768064    17928508+  82  Linux swap / Solaris

Disk /dev/md0: 481.7 GB, 481746288640 bytes
2 heads, 4 sectors/track, 117613840 cylinders, total 940910720 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
Disk identifier: 0x00000000

Disk /dev/md0 doesn't contain a valid partition table

这是我的 grub 安装输出：

root@answe:~# grub-install /dev/sda
/usr/sbin/grub-setup: warn: Attempting to install GRUB to a disk with multiple partition labels or both partition label and filesystem.  This is not supported yet..
/usr/sbin/grub-setup: error: embedding is not possible, but this is required for cross-disk install.
root@answe:~# grub-install /dev/sdb
Installation finished. No error reported.

部分版本信息：

grub-install (GRUB) 1.99-21ubuntu3.4
3.2.0-32-generic #51-Ubuntu SMP Wed Sep 26 21:33:09 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

所以

1) "update-grub" 只找到 /sda 和 /sdb Linux，而不是 /md0

2) "dpkg-reconfigure grub-pc" 说 "GRUB 无法安装以下设备 /dev/md0"

除了从 /sdb1（手动，不是自动）加载我的系统，我无法加载我的系统，并且处于降级模式......

任何人都可以解决这个问题？我对此很头疼。

更新：用零擦除新磁盘后，用 sfdisk update-grub 复制分区说：

root@answe:~# grub-install /dev/sda
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
Installation finished. No error reported.

现在 update-grub 生成相同的错误：

root@answe:~# update-grub
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
Generating grub.cfg ...
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
Found linux image: /boot/vmlinuz-3.2.0-32-generic
Found initrd image: /boot/initrd.img-3.2.0-32-generic
...
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
Found memtest86+ image: /boot/memtest86+.bin
No volume groups found
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
Found Ubuntu 12.04.1 LTS (12.04) on /dev/sda1
Found Ubuntu 12.04.1 LTS (12.04) on /dev/sdb1
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
error: found two disks with the index 2 for RAID md0.
done

Answer 1

该警告指出了根本原因。您用于替换的新磁盘可能曾经有一个文件系统，grub-setup现在被可能仍在其中的元数据混淆了。

因此，只需擦除磁盘开头到第一个分区的所有内容即可。我62从fdisk -l输出中取出了数字。它说这63是第一个分区的开始，听起来好像62在它之前有可以清理的扇区。

dd if=/dev/zero of=/dev/sda bs=512 count=62

然后重新创建分区表：

sfdisk -d /dev/sdb | sfdisk /dev/sda

sfdisk 可能会抱怨“内核可能正在使用旧的分区表”，但您可以忽略该警告，因为您并没有真正更改分区表。

那么你应该能够grub-install /dev/sda。

更新：

如果仍然出现错误，请尝试将磁盘从 RAID 中取出，并从头到尾清零更多数据。或者将整个磁盘归零 ( dd if=/dev/zero of=/dev/sda)。然后像之前一样将其添加回 RAID，从sfdisk -d /dev/sdb | sfdisk /dev/sda. 并考虑切换到元数据格式 1.0，正如其他一些地方所建议的那样。