Re: --examine contradicts --create and --detail, again

On Wed Feb 11, 2009 at 02:48:09AM -0800, whollygoat@letterboxes.org wrote:

Either I am misunderstanding something, or I have
a hardware issue I don't know how to diagnose.  Any 
suggestions on things to read or to try are welcome.

# mdadm -D /dev/md/0
    
    Number   Major   Minor   RaidDevice State
       0      33        1        0      active sync   /dev/hde1
       1      34        1        1      active sync   /dev/hdg1
       2      56        1        2      active sync   /dev/hdi1
       3      57        1        3      active sync   /dev/hdk1
       6      88        1        4      active sync   /dev/hdm1
         
       5      89        1        -      spare   /dev/hdo1

So, then, why oh why oh why does --examine, on any of the 
component devices, show slots for  7 devices, one failed, 
one empty?  I have recently changed RAM, mobo, system disk
and some IDE cables thinking each time that I had finally
come to the end of this.

# mdadm -E /dev/hde1

    Array Slot : 0 (0, 1, 2, 3, failed, empty, 4)
   Array State : Uuuuu 1 failed

Sorry for bringing up this new instance of the same old 
problem yet one more time.

I'd say this is just an artifact of how the array creation works,
Because it starts as a degraded array, initially one of the RAID devices
is flagged as missing/faulty (so you have member numbers 0, 1, 2 and 3
in the array, 4 flagged as missing/faulty, and 5 & 6 as spares).  When
it does the initial build, it uses member number 6, leaving 5 as the
spare.  This leaves you with 1 "failed" member and one "empty" (the
spare - it's not part of the array so doesn't have a Device Number).

Unfortunately I don't have any RAID5 arrays around now to check whether
I see the same here.  However, if the system's working fine otherwise
then I certainly wouldn't worry about it.

Cheers,
    Robin
-- 
     ___        
    ( ' }     |       Robin Hill        [off-list ref] |
   / / )      | Little Jim says ....                            |
  // !!       |      "He fallen in de water !!"                 |