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-   -   Unable to boot from degraded RAID array? (

sailor420 02-17-2012 05:56 PM

Unable to boot from degraded RAID array?
I have a home server running 10.04 configured with an mdadm-based RAID array. The boot and /home partitions are both on RAID-1 arrays, and I have a large data partition on RAID-5. There are three disks, with a partition from each disk making up each mdadm array--so three arrays (two RAID-1, one RAID-5), each with three disks, /dev/sda, sdb, and sdc.

Recently, /dev/sda failed, and mdadm kicked it out of the array correctly. I replaced the drive, and am now trying to boot, but when I do, I get an error "Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key." It seems that this is likely a message from my ASUS BIOS.

It seems to me that this is likely due to a missing boot loader. Am I correct in this? I'm guessing that since /dev/sda is likely what the system is trying to boot off of and since it is now a blank drive until I can boot to rebuild the array, that the machine can't boot. Oddly, I swear I remember installing GRUB to all of the disks and making sure they were bootable.

I'm tempted to change the boot order in the BIOS and see if that works, but I'm worried that doing this might somehow corrupt the now degraded RAID-5 partition (not sure why... but I'd rather not do something I don't fully understand the implications of).

How should I go about fixing this? Any help is greatly appreciated.

Guttorm 02-17-2012 06:24 PM


If the error message is from the BIOS, it probably means you lost the MBR. You can recover or rewrite it it with a live cd. Did you try one?

sailor420 02-17-2012 06:36 PM


I have not tried that--I wanted to make sure as best I could of what was going on before I did it to make sure I don't screw up the RAID array.

How would I do that, making sure that the required GRUB2 information is copied over to the new HDD to let me boot the RAID array?

Guttorm 02-18-2012 07:33 AM


Resinstalling Windows in a dual boot system also messes up the MBR, so I think you can use the same procedure:

It should be a simple command:

sudo grub-install /dev/sda

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