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Re: Grub2 reinstall on raid1 system. Corrections!!!!!


With your pastebin information and the mdstat information (that last
information in your mail and pastebins was critical good stuff) and
I found this old posting from you too:  :-)


With all of that I deduce the following:

  /dev/md125 /dev/sda1 /dev/sdc1 (10G) root partition with no lvm
  /dev/md126 /dev/sda5 /dev/sdc5 (288G) LVM for /home, /var, swap, ...
  /dev/md127 /dev/sdb /dev/sdd (465G) as yet unformatted

Jack, If that is wrong please correct me.  But I think that is right.

The mdstat data showed that the arrays are sync'd.  The UUIDs are as

  ARRAY /dev/md/125_0 metadata=0.90 UUID=e45b34d8:50614884:1f1d6a6a:d9c6914c
  ARRAY /dev/md/126_0 metadata=0.90 UUID=c06c0ea6:5780b170:ea2fd86a:09558bd1
  ARRAY /dev/md/Speeduke:2 metadata=1.2 name=Speeduke:2 UUID=91ae6046:969bad93:92136016:116577fd

The desired state:

  /dev/md0 /dev/sda1 /dev/sdc1 (10G) root partition with no lvm
  /dev/md1 /dev/sda5 /dev/sdc5 (288G) LVM for /home, /var, swap, ...

Will get to /dev/md2 later...

> My thinking is that I should rerun mdadm and reassemble the arrays to
> the original definitions...  /md0  from sda1 & sdc1
> 			     /md1  from sda5 & sdc5  note: sda2 &sdc2
> 			     are  legacy msdos extended partitions.
> I would not build a md device with msdos extended partitions under LVM2
> at this time..   Agree?

Agreed.  You want to rename the arrays.  Don't touch the msdos

> Is the above doable?  If I can figure the right mdadm commands...8-)

Yes.  It is doable.  You can rename the array.  First stop the array.
Then assemble it again with the new desired name.  Here is what you
want to do.  Tom, Henrique, others, Please double check me on these.

  mdadm --stop /dev/md125
  mdadm --assemble /dev/md0 --update=super-minor /dev/sda1 /dev/sdc1

  mdadm --stop /dev/126
  mdadm --assemble /dev/md1 --update=super-minor /dev/sda5 /dev/sdc5

That should by itself be enough to get the arrays going.

But, and this is an important but, did you previously add the new disk
array to the LVM volume group on the above array?  If so then you are
not done yet.  The LVM volume group won't be able to assemble without
the new disk.  If you did then you need to fix up LVM next.

I think you should try to get back to where you were before when your
system was working.  Therefore I would remove the new disks from the
LVM volume group.  But I don't know if you did or did not add it yet.
So I must stop here and wait for further information from you.

I don't know if your rescue disk has lvm automatically configured or
not.  You may need to load the device mapper module dm_mod.  I don't
know.  If you do then here is a hint:

  modprobe dm_mod

To scan for volume groups:


To activate a volume group:

  vgchange -ay

To display the physical volumes associated with a volume group:


If the new disks haven't been added to the volume group (I am hoping
not) then you should be home free.  But if they are then I think you
will need to remove them first.

I don't know if the LVM actions above are going to be needed.  I am
just trying to proactively give some possible hints.


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