Hi,
Got the problems solved. I couldn't solve the problem by using the rescue
disk, as it wouldn't let me stop the raid array.
What I did was drop into the maintenance mode:
mdadm --assemble /dev/md1 /dev/sdd1 /dev/sde1   //This should recreate the
array
mdadm --detail --scan >> /etc/mdadm/mdadm.conf

//edit the file to remove duplicates
dpkg-reconfigure linux-image-$(uname -r)

then reboot.

Huge amount of thanks go to Bob Proulx for all the help along the way,
James



On 7 July 2013 21:53, James Allsopp <jamesaalls...@googlemail.com> wrote:

> Hello,
> I've been too nervous to reboot, so I've left it in the rescue mode at the
> point where I assembled the raid arrays and went into boot at the \
> partition.
> Tried to run:
>   mdadm --stop /dev/md127
> but got a mdadm: failed to stop array /dev/md127: Device or resource busy.
> Perhaps a running process, mounted filesustem or active volume group?
>
> I tried unmounting /home which stretches onto this disk via LVM, but this
> made no difference. Any idea how I should proceed?
> Thanks,
> James
>
>
>
> On 5 July 2013 01:10, Bob Proulx <b...@proulx.com> wrote:
>
>> James Allsopp wrote:
>> > I'd like to hear about the optimisations, but I think I'll wait till I
>> get
>> > the system rebuilt!
>>
>> Basically I had expected you to use either rescue mode of the d-i or a
>> livecd or other to assemble the arrays.  You did.  But neither array
>> came up completely correct.  One came up with one disk degraded.  The
>> split brain clone came up on md127 instead of md0.  The other one came
>> up on md126.  So you should fix those using the discussed
>> instructions.  I was thinking you would do that from the same system
>> boot that you had posted that information from.
>>
>> But your recent mail implies that you shut the system down and went
>> away for a while.  So now it appears you need to "rescue" the system
>> again by the same method you used to get that information you posted.
>>
>> All of that is fine.  Except now we already know the information you
>> posted.  And so now we know how those arrays are supposed to go
>> together.  But that is okay.  You can go through rescue mode and
>> assemble the arrays exactly as you did before.  And then --stop the
>> arrays and assemble them correctly.
>>
>> But since we know how they are supposed to be assembled now you could
>> skip the assembly of them in rescue mode or livecd mode or whatever
>> you used and simply assemble the arrays correctly the first time.
>> Basically I think you are going to do:
>>
>>  * rescue
>>  * assemble arrays
>>  * stop arrays
>>  * assemble arrays correctly
>>
>> Which is perfectly acceptable.  The result will be fine.  But now that
>> we know what we need to do you could simply do this:
>>
>>  * rescue
>>  * assemble arrays correctly
>>
>> But I don't want to distract you with complications like this! :-)
>>
>> And then after you get everything working you should visit the
>> partitioning on that second array.  Your partitioning starts at the
>> sector 1.  But that won't be aligned.  It will cause all writes to be
>> a read-modify-write and performance will suffer.
>>
>> >    Device Boot      Start         End      Blocks   Id  System
>> > /dev/sdd1               1      243201  1953512001   fd  Linux raid
>> autodetect
>> > Partition 1 does not start on physical sector boundary.
>> >    Device Boot      Start         End      Blocks   Id  System
>> > /dev/sde1               1      243201  1953512001   fd  Linux raid
>> autodetect
>> > Partition 1 does not start on physical sector boundary.
>>
>> Instead of using the entire disk starting at 1 it would be much better
>> if you started at sector 2048 as is the new standard for Advanced
>> Format 4k sector drives.  I would expect that to be a large
>> performance lever on your system.  But fix that after you have your
>> data up and available.
>>
>> Bob
>>
>
>

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