WAS "A Fail event had been detected on md device /dev/md0" NOW Kernel Panic...

[TonyMLake]

Hello,

I'm new so I'm not sure I am providing all the correct information. I'm running CentOS 5.8. Today I got an email that said

"A Fail event had been detected on md device /dev/md0.

It could be related to component device /dev/sda1."

I was unsure, but I thought the following might work to restore the system:

I ran "cat /proc/mdstat" and got:

[code]
Personalities : [raid6] [raid5] [raid4] [raid1]
md0 : active raid1 sda1[2](F) sdb1[1] sdc1[0]
256896 blocks [2/2] [UU]

md2 : active raid5 sdc2[2] sdb2[1] sda2[3](F)
20482560 blocks level 5, 256k chunk, algorithm 2 [3/2] [_UU]

md1 : active raid5 sdc5[2] sdb5[1] sda5[3](F)
198627328 blocks level 5, 256k chunk, algorithm 2 [3/2] [_UU]

unused devices: <none>

[/code]


I believe this meant sda had failed. I wanted to do the following:


[code]
mdadm --manage /dev/md0 --fail /dev/sda1
mdadm --manage /dev/md1 --fail /dev/sda5
mdadm --manage /dev/md2 --fail /dev/sda2
[/code]


shutdown

replace the dead disk

boot


[code]
fdisk -l /dev/sda

mdadm --manage /dev/md0 --add /dev/sda1
mdadm --manage /dev/md1 --add /dev/sda5
mdadm --manage /dev/md2 --add /dev/sda2
[/code]


Unfortunately, when I tried to boot, I got a message that said something like
"kernel panic not syncing attempted to kill init"

Probably because not everything that was needed to boot the machine was copied to the two disks remaining in the array (?)


I know next to nothing about linux relative to most of you, so, even the most basic assistance would need to be very simply worded... still... can someone help me restore this system?



Thank you very much!


Tony

[ScreamingWeasel]

Boot into rescue mode with your installation media, and manipulate the array to get it functional. Then run grub-install, and reboot.

[TonyMLake]

Can I boot into rescue mode with the NetInstall CD ?

[pschaff]

Welcome to the CentOS fora. Please see the recommended reading for new users linked in my signature.

[quote]
TonyMLake wrote:
Can I boot into rescue mode with the NetInstall CD ?[/quote]
No. You need to use full installation media - CD1 or DVD1.