On Mon, Jan 28, 2013 at 08:00:35PM +0100, Wolfgang Denk wrote:

Dear Piergiorgio,

In message [ref] you wrote:

quoted

I would shamelessly suggest to try "raid6check", in order
to see if some components have problems.

The software is somehow buried into "mdadm" source code,
probably you'll need to take it from the repository.

Found it.  Thanks for the suggestion.

However, this is extreme verbose:

layout: 2
disks: 8
component size: 249108103168
total stripes: 15204352
chunk size: 16384

disk: 0 - offset: 134217728 - size: 250864926720 - name: /dev/sdk1 -
slot: 5
disk: 1 - offset: 134217728 - size: 250864926720 - name: /dev/sdj1 -
slot: 4
disk: 2 - offset: 134217728 - size: 250864926720 - name: /dev/sdi1 -
slot: 7
disk: 3 - offset: 134217728 - size: 250864926720 - name: /dev/sdh1 -
slot: 3
disk: 4 - offset: 134217728 - size: 250864926720 - name: /dev/sdg1 -
slot: 2
disk: 5 - offset: 134217728 - size: 250864926720 - name: /dev/sdf1 -
slot: 1
disk: 6 - offset: 134217728 - size: 250864926720 - name: /dev/sde1 -
slot: 6
disk: 7 - offset: 134217728 - size: 250863844352 - name: /dev/sdd1 -
slot: 0

pos --> 0
0->1
1->2
2->3
3->4
4->5
5->6
pos --> 1
0->0
1->1
2->2
3->3
4->4
5->5
pos --> 2
0->7
1->0
2->1
3->2
4->3
5->4
pos --> 3
0->6
1->7
2->0
3->1
4->2
5->3
pos --> 4
0->5
1->6
2->7
3->0
4->1
5->2
pos --> 5
...

etc. ad nauseam.  I guess "pos" means stripe here, so it would print
this for all stripes in the array?  Does this means all of them are
broken?  Or what would I  have to look for to see where an error
mightbe?

Hi Wolfgang,

the output is indeed verbose, my suggestion would be
to redirect it to a file (on different storage) and
"grep" later for "Error".
This should report if a specific device is detected
with problems or if it cannot detect which device.

The output you see above means everything is correct,
until stripe 4, at least. So you're right, the "pos"
is the stripe position.

In case of error, something like:

Error detected at X: possible failed disk slot: Y

Which means stripe X, disk Y, from the initial print.

Or it could be:

Error detected at X: disk slot unknown

Which should be obvious.

Hope this helps,

bye,

-- 

piergiorgio