Re: Upgrade from Ubuntu 10.04 to 12.04 broken raid6.

[EJ Vincent <ej@ejane.org>]

On 9/30/2012 4:28 PM, Phil Turmel wrote:
> On 09/30/2012 03:25 PM, EJ Vincent wrote:
>> On 9/30/2012 3:22 PM, Mathias Burén wrote:
>>> Can't you just boot off an older Ubuntu USB, install mdadm and scan /
>>> assemble, see the device order?
>> Hi Mathias,
>>
>> I'm under the impression that damage to the metadata has already been
>> done by 12.04, making a recovery from an older version of Ubuntu
>> (10.04), impossible.  Is this line of thinking, flawed?
> Your impression is correct.  Permanent damage to the metadata was done.
>   You *must* re-create your array.
>
> However, you *cannot* use your new version of mdadm, as it will get the
> data offset wrong.  Your first report showed a data offset of 272.
> Newer versions of mdadm default to 2048.  You *must* perform all of your
> "mdadm --create --assume-clean" permutations with 10.04.
>
> Do you have *any* dmesg output from the old system?  Or dmesg from the
> very first boot under 12.04?  That might have enough information to
> shorten your search.
>
> In the future, you should record your setup by saving the output of
> "mdadm -D" on each array, "mdadm -E" on each member device, and the
> output of "ls -l /dev/disk/by-id/"
>
> Or try my documentation script "lsdrv". [1]
>
> HTH,
>
> Phil
>
> [1] http://github.com/pturmel/lsdrv
>
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Hi Phil,

Unfortunately I don't have any dmesg log from the old system or the 
first boot under 12.04.

Getting my system to boot at all under 12.04 was chaotic enough, with 
the overly-aggressive /usr/share/initramfs-tools/scripts/mdadm-functions 
ravaging my array and then dropping me to a busybox shell over and over 
again.  I didn't think to record the very first error.

Here's an observation of mine, disks: /dev/sdb1, /dev/sdi1, and 
/dev/sdj1 don't have the Raid level "-unknown-", neither are they 
labeled as spares.  They are in fact, labeled clean and appear 
*different* from the others.

Could these disks still contain my metadata from 10.04?  I recall during 
my installation of 12.04 I had anywhere from 1 to 3 disks unpowered, so 
that I could drop in a SATA CD/DVDRW into the slot.

I am downloading 10.04.4 LTS and will be ready to use it soon.  I fear 
having to do permutations-- 9! (factorial) would mean 362,880 
combinations.  *gasp*

Many thanks for all your comments and insights.

-EJ
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