Re: RAID array is gone, please help

[Stephen Mueller]

Looks like it worked! Thanks!

I used:

sudo mdadm --create /dev/md0 --assume-clean --verbose --level-10 
--raid-devices=4 /dev/sdc /dev/sdd /dev/sde /dev/sdf

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


On 3/23/2017 21:09, Stephen Mueller wrote:
> OK, I used gdisk to remove the GPT and MBR from each disk.
> mdadm --assemble still doesn't work... says it can't find the
> superblock. The mdadm --examine commands also say that no
> superblock is detected.
>
> I guess I'll go ahead with --create...
>
>
> On 3/23/2017 20:59, Lennart Sorensen wrote:
> > On Thu, Mar 23, 2017 at 08:38:08PM +0100, Stephen Mueller wrote:
> > > Apologies, I should have started this on linux-raid...
> > >
> > >
> > > stephen@fred> sudo gdisk -l /dev/sdc
> > > GPT fdisk (gdisk) version 1.0.1
> > >
> > > Partition table scan:
> > >   MBR: protective
> > >   BSD: not present
> > >   APM: not present
> > >   GPT: present
> > >
> > > Found valid GPT with protective MBR; using GPT.
> > > Disk /dev/sdc: 7814037168 sectors, 3.6 TiB
> > > Logical sector size: 512 bytes
> > > Disk identifier (GUID): 60F1D54C-9D17-4688-BD6E-447F5E7408EB
> > > Partition table holds up to 128 entries
> > > First usable sector is 34, last usable sector is 7814037134
> > > Partitions will be aligned on 2048-sector boundaries
> > > Total free space is 7814037101 sectors (3.6 TiB)
> > >
> > > Number  Start (sector)    End (sector)  Size       Code  Name
> > > stephen@fred>
> > >
> > > The other disks are all similar.
> > >
> > > How do I remove the MBR/GPT tables? So you would do that, and then the
> > > mdadm --create?
> >
> > Well at least that seems to confirm that something restored the GPT from
> > the second copy at the end of the disk, wiping out the md superblock
> > at 4k.
> >
> > If you run gdisk /dev/sdc, it has a 'zap' option using the z key to
> > delete all traces of GPT.  That ought to do what you want.