Ubuntu 12.04 boot degraded raid
- by beacon_bonanza
I've installed Ubuntu 12.04.1 in a new server and set up the 4 hard drives with 3 RAID 1 devices, the configuration is such that the first two drives have md0 (swap space) and md1 (/) with the third and fourth drives having md2 (/var).
I've been testing the operation under a drive failure and found that the system boots fine if I remove disk two but if I remove disk one then the system gets to grub and then just restarts. I'm confused as to why grub appears to be loading properly from disk two but then the boot fails.
I've tried to copy the MBR from disk 1 to 2:
dd if=/dev/sda of=/dev/sdb bs=512 count=1
but this didn't make a difference.
Any ideas how to get it to boot from just the second disk?
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/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/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/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/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/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