我在新服务器中安装了 Ubuntu 12.04.1，并设置了 4 个硬盘驱动器和 3 个 RAID 1 设备，配置是前两个驱动器具有 md0（交换空间）和 md1 (/)，第三个和第四个驱动器具有 md0（交换空间）和 md1 (/)具有 md2 (/var) 的驱动器。
我一直在测试驱动器故障下的操作，发现如果删除磁盘 2，系统可以正常启动，但如果删除磁盘 1，系统就会进入 grub，然后重新启动。我很困惑为什么 grub 似乎可以从磁盘 2 正确加载，但启动失败。
我尝试将 MBR 从磁盘 1 复制到磁盘 2：
dd if=/dev/sda of=/dev/sdb bs=512 count=1
但这并没有什么区别。
grub配置文件
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
}
insmod raid
insmod mdraid1x
insmod part_msdos
insmod part_msdos
insmod ext2
set root='(mduuid/bec69e6b53a222d6726d1f6a11d27043)'
search --no-floppy --fs-uuid --set=root c3a8948c-4ca8-4d3b-acbe-64baa0f7a181
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=auto
load_video
insmod gfxterm
insmod raid
insmod mdraid1x
insmod part_msdos
insmod part_msdos
insmod ext2
set root='(mduuid/bec69e6b53a222d6726d1f6a11d27043)'
search --no-floppy --fs-uuid --set=root c3a8948c-4ca8-4d3b-acbe-64baa0f7a181
set locale_dir=($root)/boot/grub/locale
set lang=en_GB
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ]; then
set timeout=-1
else
set timeout=2
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###
### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
if [ "${linux_gfx_mode}" != "text" ]; then load_video; fi
menuentry 'Ubuntu, with Linux 3.2.0-29-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod raid
insmod mdraid1x
insmod part_msdos
insmod part_msdos
insmod ext2
set root='(mduuid/bec69e6b53a222d6726d1f6a11d27043)'
search --no-floppy --fs-uuid --set=root c3a8948c-4ca8-4d3b-acbe-64baa0f7a181
linux /boot/vmlinuz-3.2.0-29-generic root=UUID=c3a8948c-4ca8-4d3b-acbe-64baa0f7a181 ro
initrd /boot/initrd.img-3.2.0-29-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-29-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod raid
insmod mdraid1x
insmod part_msdos
insmod part_msdos
insmod ext2
set root='(mduuid/bec69e6b53a222d6726d1f6a11d27043)'
search --no-floppy --fs-uuid --set=root c3a8948c-4ca8-4d3b-acbe-64baa0f7a181
echo 'Loading Linux 3.2.0-29-generic ...'
linux /boot/vmlinuz-3.2.0-29-generic root=UUID=c3a8948c-4ca8-4d3b-acbe-64baa0f7a181 ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-29-generic
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
insmod raid
insmod mdraid1x
insmod part_msdos
insmod part_msdos
insmod ext2
set root='(mduuid/bec69e6b53a222d6726d1f6a11d27043)'
search --no-floppy --fs-uuid --set=root c3a8948c-4ca8-4d3b-acbe-64baa0f7a181
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
insmod raid
insmod mdraid1x
insmod part_msdos
insmod part_msdos
insmod ext2
set root='(mduuid/bec69e6b53a222d6726d1f6a11d27043)'
search --no-floppy --fs-uuid --set=root c3a8948c-4ca8-4d3b-acbe-64baa0f7a181
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###
### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###
### BEGIN /etc/grub.d/41_custom ###
if [ -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
mdadm配置
:~$ mdadm /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Wed Aug 29 10:28:02 2012
Raid Level : raid1
Array Size : 15615872 (14.89 GiB 15.99 GB)
Used Dev Size : 15615872 (14.89 GiB 15.99 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon Sep 3 10:35:25 2012
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name : norsewind-obs:0 (local to host norsewind-obs)
UUID : b55552d2:1e554573:82671934:3831d058
Events : 19
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
:~$ sudo mdadm -D /dev/md1
Version : 1.2
Creation Time : Wed Aug 29 10:28:11 2012
Raid Level : raid1
Array Size : 1937758016 (1847.99 GiB 1984.26 GB)
Used Dev Size : 1937758016 (1847.99 GiB 1984.26 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon Sep 3 10:47:40 2012
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name : norsewind-obs:1 (local to host norsewind-obs)
UUID : bec69e6b:53a222d6:726d1f6a:11d27043
Events : 263
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
2 8 18 1 active sync /dev/sdb2
磁盘驱动器
:~$ sudo fdisk -l
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 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: 0x000ccfa5
Device Boot Start End Blocks Id System
/dev/sda1 2048 31250431 15624192 fd Linux RAID autodetect
/dev/sda2 * 31250432 3907028991 1937889280 fd Linux RAID autodetect
Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 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: 0x000ccfa5
Device Boot Start End Blocks Id System
/dev/sdb1 2048 31250431 15624192 fd Linux RAID autodetect
/dev/sdb2 * 31250432 3907028991 1937889280 fd Linux RAID autodetect
Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 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: 0x000c73aa
Device Boot Start End Blocks Id System
/dev/sdc1 2048 3907028991 1953513472 fd Linux RAID autodetect
Disk /dev/sdd: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 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: 0x00035b05
Device Boot Start End Blocks Id System
/dev/sdd1 2048 3907028991 1953513472 fd Linux RAID autodetect
Disk /dev/md2: 2000.3 GB, 2000263380992 bytes
2 heads, 4 sectors/track, 488345552 cylinders, total 3906764416 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/md2 doesn't contain a valid partition table
Disk /dev/md0: 16.0 GB, 15990652928 bytes
2 heads, 4 sectors/track, 3903968 cylinders, total 31231744 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
Disk /dev/md1: 1984.3 GB, 1984264208384 bytes
2 heads, 4 sectors/track, 484439504 cylinders, total 3875516032 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/md1 doesn't contain a valid partition table
答案1
使用grub-install而不是dd将 grub 安装到 MBR 中。
例如（作为 root，或使用 sudo）：
grub-install /dev/sda
grub-install /dev/sdb
顺便说一句，除非您休眠到交换分区，否则交换设备上不需要 RAID。您最好销毁 md0 并分别使用 sda 和 sdb 上的交换分区。