Re: RAID array is gone, please help

[Stephen Mueller <stephen@mueller.org>]

First I'm getting the data off the RAID... then I'm going to delete the 
whole thing again... create a new RAID using partitions... follow every 
step carefully... then once the new RAID array is there, I'll throw a
bit of data on it, and then reboot and see if it's still there...
if so, I'll repopulate all the data. Thanks.

On 3/23/2017 22:09, Lennart Sorensen wrote:
> On Thu, Mar 23, 2017 at 10:02:23PM +0100, Stephen Mueller wrote:
>> Looks like it worked! Thanks!
>
> Well at least you could backup the data, just in case.
>
>> I used:
>>
>> sudo mdadm --create /dev/md0 --assume-clean --verbose --level-10
>> --raid-devices=4 /dev/sdc /dev/sdd /dev/sde /dev/sdf
>
> I wonder about the assume-clean, but I would think any data you wrote
> will have been duplicated at the time you wrote it, and only unused
> space might not have been synced yet.
>
> Maybe running a forced resync would be worthwhile.
>
>> And I got my instructions for creating the array here, and they
>> also don't use partitions...
>>
>> https://www.digitalocean.com/community/tutorials/how-to-create-raid-arrays-with-mdadm-on-ubuntu-16-04
>
> Well it works, as long as you don't leave anything around to confuse it,
> in this case a GPT partition table that somehow came back to bite you.
>
> I wonder if mdadm could perhaps warn about the existing partition table
> when being asked to create a new device.
>
> Does it survive reboots now?
>