Re:Server down-fail​ed RAID5-asking for some assistance

[John Valarti <mdadmuser@gmail.com>]

On Thu, Apr 21, 2011 at 1:59 PM, David Brown <david.brown@hesbynett.no> wrote:
.
> My first thought would be to get /all/ the disks, not just the "failed"
> ones, out of the machine.  You want to make full images of them (with
> ddrescue or something similar) to files on another disk, and then work with
> those images.  ..
> Once you've got some (hopefully most) of your data recovered from the
> images, buy four /new/ disks to put in the machine, and work on your
> restore.  You don't want to reuse the failing disks, and probably the other
> two equally old and worn disks will be high risk too.

OK, I think I understand.
Does that mean I need to buy 8 disks, all the same size or bigger?
The originals are 250GB SATA so that should be OK, I guess.

I read some more and found out I should run mdadm --examine.

Should I not be able to just add the one disk partition sdc2 back to the RAID?


Here is the result of --examine

/dev/sda2:
         Magic : a92b4efc
       Version : 0.90.00
          UUID : ddf4d448:36afa319:f0917855:03f8bbe8
 Creation Time : Mon May 15 16:38:05 2006
    Raid Level : raid5
 Used Dev Size : 244975104 (233.63 GiB 250.85 GB)
    Array Size : 734925312 (700.88 GiB 752.56 GB)
  Raid Devices : 4
 Total Devices : 3
Preferred Minor : 1

   Update Time : Mon Apr 18 07:48:54 2011
         State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
 Spare Devices : 0
      Checksum : 5674ce60 - correct
        Events : 28580020

        Layout : left-symmetric
    Chunk Size : 256K

     Number   Major   Minor   RaidDevice State
this     1       8       18        1      active sync   /dev/sdb2

  0     0       8        2        0      active sync   /dev/sda2
  1     1       8       18        1      active sync   /dev/sdb2
  2     2       8       34        2      active sync   /dev/sdc2
  3     3       0        0        3      faulty removed
/dev/sdb2:
         Magic : a92b4efc
       Version : 0.90.00
          UUID : ddf4d448:36afa319:f0917855:03f8bbe8
 Creation Time : Mon May 15 16:38:05 2006
    Raid Level : raid5
 Used Dev Size : 244975104 (233.63 GiB 250.85 GB)
    Array Size : 734925312 (700.88 GiB 752.56 GB)
  Raid Devices : 4
 Total Devices : 4
Preferred Minor : 1

   Update Time : Sun Oct 18 10:04:06 2009
         State : active
Active Devices : 4
Working Devices : 4
Failed Devices : 0
 Spare Devices : 0
      Checksum : 5171dcb2 - correct
        Events : 20333614

        Layout : left-symmetric
    Chunk Size : 256K

     Number   Major   Minor   RaidDevice State
this     3       8       50        3      active sync   /dev/sdd2

  0     0       8        2        0      active sync   /dev/sda2
  1     1       8       18        1      active sync   /dev/sdb2
  2     2       8       34        2      active sync   /dev/sdc2
  3     3       8       50        3      active sync   /dev/sdd2
/dev/sdc2:
         Magic : a92b4efc
       Version : 0.90.00
          UUID : ddf4d448:36afa319:f0917855:03f8bbe8
 Creation Time : Mon May 15 16:38:05 2006
    Raid Level : raid5
 Used Dev Size : 244975104 (233.63 GiB 250.85 GB)
    Array Size : 734925312 (700.88 GiB 752.56 GB)
  Raid Devices : 4
 Total Devices : 3
Preferred Minor : 1

   Update Time : Mon Apr 18 07:48:51 2011
         State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
 Spare Devices : 0
      Checksum : 5674ce6b - correct
        Events : 28580018

        Layout : left-symmetric
    Chunk Size : 256K

     Number   Major   Minor   RaidDevice State
this     2       8       34        2      active sync   /dev/sdc2

  0     0       8        2        0      active sync   /dev/sda2
  1     1       8       18        1      active sync   /dev/sdb2
  2     2       8       34        2      active sync   /dev/sdc2
  3     3       0        0        3      faulty removed
/dev/sdd2:
         Magic : a92b4efc
       Version : 0.90.00
          UUID : ddf4d448:36afa319:f0917855:03f8bbe8
 Creation Time : Mon May 15 16:38:05 2006
    Raid Level : raid5
 Used Dev Size : 244975104 (233.63 GiB 250.85 GB)
    Array Size : 734925312 (700.88 GiB 752.56 GB)
  Raid Devices : 4
 Total Devices : 3
Preferred Minor : 1

   Update Time : Mon Apr 18 07:48:54 2011
         State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
 Spare Devices : 0
      Checksum : 5674ce4e - correct
        Events : 28580020

        Layout : left-symmetric
    Chunk Size : 256K

     Number   Major   Minor   RaidDevice State
this     0       8        2        0      active sync   /dev/sda2

  0     0       8        2        0      active sync   /dev/sda2
  1     1       8       18        1      active sync   /dev/sdb2
  2     2       8       34        2      active sync   /dev/sdc2
  3     3       0        0        3      faulty removed
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