Hi Neil,

On Sun, May 05, 2013 at 12:58:27PM +1000, NeilBrown wrote:

On Sat, 4 May 2013 18:30:06 +0200 Piergiorgio Sartor
[off-list ref] wrote:

quoted

Hi Rudy,

thanks for the answer, but as mentioned at the end,
"--force" assemby does not work.
Reason is, 7 disks complains 3 are missing and the
3 missing are assembed, since their superblock does
not report errors.
Of course, 3 disks are not enough to assembly the
array, forced or not.

Details please.  "--examine" output of every device would be a good start.
Output for "mdadm --assemble --force --verbose ....."
would help too.

thanks for the answer.
As mentioned in a sequent post, I fixed it by hex editing
the superblock and restoring, in the 7 disks, the other 3
missing.

Anyway, I did not considered the "--verbose" option, thanks
for the hint.

Thanks again,

bye,

pg

NeilBrown

quoted

bye,

pg

On Sat, May 04, 2013 at 04:22:39PM +0000, Rudy Zijlstra wrote:

quoted

Hi

I would start with mdadm assemble --force

Do not use create unless all else has failed

Cheers

Rudy
---
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-----Original Message-----
From: Piergiorgio Sartor <redacted>
Sender: linux-raid-owner@vger.kernel.org
Date:	Sat, 4 May 2013 18:08:04 
To: <redacted>
Subject: RAID-6 with 3 missing disks

Hi all,

I know this was probably already discussed, but
maybe I need some refresh.

I've a 10 HDDs RAID-6 which, due to mishap (disks
were disconnected accidentaly), has now 3 missing
devices and cannot be assembled.
The data should be OK, since no writes were occurring
during the accident, so putting them together again
should work.

As far as I know, one option is to create, with
"mdadm -C" the array again, giving the disks in
the proper order.

Since all HDDs are readable, I guess "mdadm -E"
should return the role of each device.
Is this correct for the creation order?

Second question is about the "Data Offset", since
this array was created with an older version of
"mdadm" and the data offset is very close to the
superblock.
As far as I know, new mdadm creates the data a
bit far aways.
Is there any way to specifiy the proper offset?

Finally, is there an alternative to "mdadm -C"
or it is the only option?
Forcing assembly does not work, but maybe there
is another way to tell mdadm to really assemby
the array, taking into account the superblock
information, which are all readable.

Thanks a lot in advance,

bye,

-- 

piergiorgio
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piergiorgio