From: Eric Shubert <ejs@shubes.net>
> On 10/19/2011 01:06 AM, James Dugger wrote:
>> fdisk -l gives the following:
>> /dev/sda1 1 121601 976760001 83 Linux
>> /dev/sdb1 1 121601 976760001 83 Linux
>> /dev/sdc1 1 121601 976760001 83 Linux
>> /dev/sdd1 1 121601 976760001 83 Linux
>> /dev/sde1 * 1 32 248832 83 Linux
>> /dev/sde2 32 60802 488134657 5 Extended
>> /dev/sde5 32 60802 488134656 8e Linux LVM
So sde contains /boot and / , while you'd like to have sda..sdd contain the
RAID. This should work, but for some reason mdadm says:
>> 0 0 8 49 0 active sync /dev/sdd1
>> 1 1 8 33 1 active sync /dev/sdc1
>> 2 2 8 17 2 active sync /dev/sdb1
>> 3 3 8 65 3 active sync /dev/sde1
I'm very surprised anything's working at all if it's trying to use sde1 as a
component of the RAID.
>> Notice the md3 device at the bottom of the fdisk print out.
md devices can contain partition tables if you really want them to. Some
people do this; I wouldn't.
> Looks like from the --examine that the device assignments (/dev/sd?)
> have moved around since the array was created (sda belongs to an array
> consisting of d,c,b,e).
Hm. I thought mdadm went by UUIDs within the RAID superblocks, not partition
names.
> Have a look at:
> # ls -l /dev/disk/by_id
> and it'll show which drives are assigned to which /dev/sd? letter.
>
> Then (w/out rebooting) take another crack at clearing things out, with:
> # mdadm --zero-superblock ...
> Then re-create/build the array.
This may not work properly if mdadm has the superblocks tangled up. You could
zorch the superblocks yourself with dd, something like "dd if=/dev/zero
of=/dev/sda bs=1M seek=1013760" , repeated for each of the disks. (That's
"seek 990G out and start writing zeroes", it'll take a lot less time than
dding /dev/zero over the entire 1T disk.) Then stop md3 (if possible without
rebooting), then recreate it, using the right options for RAID10 and the right
disk names. I'd change the partition types of the softRAID components to 0xfd
too, just because that makes it a little clearer as to what's going on, but
that may be old-school or deprecated now or something.
Have a rescue CD handy if your /boot has been eaten by this mdadm
misadventure. That's workaroundable, just not usually all that fun.
--
Matt G / Dances With Crows
The Crow202 Blog: http://crow202.org/wordpress/
There is no Darkness in Eternity/But only Light too dim for us to see