On Sun, 5 Oct 2014 02:38:53 -0700 Jean-Paul Sergent [off-list ref]
wrote:

haha, you're awesome, did an apt-get update && apt-get install mdadm.
Got version:

mdadm - v3.3.2 - 21st August 2014

and all is good, re-added drives automatically, threw out the one with
the oldest event, which had bad sectors.

Excellent :-)

Thanks so much.

One last question though, the filesystem was XFS. Should I repair the
degraded raid first with a spare disk? or should I do an xfs scrub
first?

It hardly matters.  If another device is going to fail, either action could
cause it by putting stress on the system.  If not, doing both in parallel is
perfectly safe.

If you have some really really important files, it might make sense to copy
them off before doing anything else.
I would probably start the array recovering, then start running the xfs scrub
tool.

NeilBrown

-JP

On Sun, Oct 5, 2014 at 2:21 AM, Jean-Paul Sergent [off-list ref] wrote:

quoted

I'm recovering with a liveUSB of debian, the system this raid is on
normally runs fedora 20, I'm not sure what version of mdadm was
running on that system. I can find out if I need to.


root@debian:~# mdadm --version
mdadm - v3.3 - 3rd September 2013


root@debian:~# mdadm -A /dev/md0 --force -vv /dev/sdb /dev/sdc
/dev/sde /dev/sdf /dev/sdg
mdadm: looking for devices for /dev/md0
mdadm: /dev/sdb is identified as a member of /dev/md0, slot 2.
mdadm: /dev/sdc is identified as a member of /dev/md0, slot 1.
mdadm: /dev/sde is identified as a member of /dev/md0, slot 0.
mdadm: /dev/sdf is identified as a member of /dev/md0, slot 3.
mdadm: /dev/sdg is identified as a member of /dev/md0, slot 4.
mdadm: added /dev/sdc to /dev/md0 as 1
mdadm: added /dev/sdb to /dev/md0 as 2
mdadm: added /dev/sdf to /dev/md0 as 3 (possibly out of date)
mdadm: added /dev/sdg to /dev/md0 as 4 (possibly out of date)
mdadm: added /dev/sde to /dev/md0 as 0
mdadm: /dev/md0 assembled from 3 drives - not enough to start the array.

Thanks,
-JP

On Sun, Oct 5, 2014 at 1:41 AM, NeilBrown [off-list ref] wrote:

quoted

On Sat, 4 Oct 2014 22:43:01 -0700 Jean-Paul Sergent [off-list ref]
wrote:

quoted

Greetings,

Recently I lost 2 disks, out of 5, in my raid 5 array from a bad SATA power
cable. It was a Y splitter and it shorted... it was cheap. I was wondering
if there was any chance in getting my data back.

Of the 2 disks that blew out, one actually had bad/unreadable sectors on
the disk and the other disk seems fine. I have cloned both disks with DD to
2 new disks and forced the one disk to clone even with errors. The
remaining 3 disks are in tact. The events number on the array for all 5
disks are very close to each other:

         Events : 201636
         Events : 201636
         Events : 201636
         Events : 201630
         Events : 201633

Which from my reading gives me some hope, but I'm not sure. I have not done
"recovering a failed software raid" on the wiki yet, the part about
using a loop device to protect your array. I thought I would send a
message out to this list first before going down
that route.

I did try to do a mdadm --force --assemble on the array but is says that it
only has 3 disks which isn't enough to start the array. I don't want to do
anything else before consulting the mailing list first.

--force --assemble really is what you want.  It should work.
What does
   mdadm -A /dev/md1 --force -vv /dev/sdb /dev/sdc /dev/sde /dev/sdf /dev/sdg

report??
What version of mdadm (mdadm -V) do you have?

NeilBrown

quoted

below I have pasted the mdadm --examine from each member drive. Any help would
be greatly appreciated.

Thanks,
-JP

/dev/sdb:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 7de100f5:4f30f751:62456293:fe98f735
           Name : b1ackb0x:1
  Creation Time : Sun Jan 13 00:01:44 2013
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 2930275120 (1397.26 GiB 1500.30 GB)
     Array Size : 5860548608 (5589.05 GiB 6001.20 GB)
  Used Dev Size : 2930274304 (1397.26 GiB 1500.30 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1968 sectors, after=816 sectors
          State : clean
    Device UUID : 71d7c3d7:7b232399:51571715:711da6f6

    Update Time : Tue Apr 29 02:49:21 2014
       Checksum : cd29f83c - correct
         Events : 201636

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 2
   Array State : AAA.. ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdc:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 7de100f5:4f30f751:62456293:fe98f735
           Name : b1ackb0x:1
  Creation Time : Sun Jan 13 00:01:44 2013
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 2930275120 (1397.26 GiB 1500.30 GB)
     Array Size : 5860548608 (5589.05 GiB 6001.20 GB)
  Used Dev Size : 2930274304 (1397.26 GiB 1500.30 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1968 sectors, after=816 sectors
          State : clean
    Device UUID : b47c32b5:b2f9e81a:37150c33:8e3fa6ca

    Update Time : Tue Apr 29 02:49:21 2014
       Checksum : 1e5353af - correct
         Events : 201636

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 1
   Array State : AAA.. ('A' == active, '.' == missing, 'R' == replacing)
/dev/sde:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 7de100f5:4f30f751:62456293:fe98f735
           Name : b1ackb0x:1
  Creation Time : Sun Jan 13 00:01:44 2013
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 2930275120 (1397.26 GiB 1500.30 GB)
     Array Size : 5860548608 (5589.05 GiB 6001.20 GB)
  Used Dev Size : 2930274304 (1397.26 GiB 1500.30 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1968 sectors, after=816 sectors
          State : clean
    Device UUID : 0398da5b:0bcddd81:8f7e77e9:6689ee0c

    Update Time : Tue Apr 29 02:49:21 2014
       Checksum : 24a3f586 - correct
         Events : 201636

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 0
   Array State : AAA.. ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdf:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 7de100f5:4f30f751:62456293:fe98f735
           Name : b1ackb0x:1
  Creation Time : Sun Jan 13 00:01:44 2013
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 2930275120 (1397.26 GiB 1500.30 GB)
     Array Size : 5860548608 (5589.05 GiB 6001.20 GB)
  Used Dev Size : 2930274304 (1397.26 GiB 1500.30 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1968 sectors, after=976752816 sectors
          State : clean
    Device UUID : 356c6d85:627a994f:753dec0d:db4fa4f2

    Update Time : Tue Apr 29 02:37:38 2014
       Checksum : 2621f9d5 - correct
         Events : 201630

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 3
   Array State : AAAAA ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdg:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 7de100f5:4f30f751:62456293:fe98f735
           Name : b1ackb0x:1
  Creation Time : Sun Jan 13 00:01:44 2013
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 2930275120 (1397.26 GiB 1500.30 GB)
     Array Size : 5860548608 (5589.05 GiB 6001.20 GB)
  Used Dev Size : 2930274304 (1397.26 GiB 1500.30 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1968 sectors, after=976752816 sectors
          State : clean
    Device UUID : 3dc152d8:832dd43a:a6d638e3:6e12b394

    Update Time : Tue Apr 29 02:48:01 2014
       Checksum : db9e6008 - correct
         Events : 201633

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 4
   Array State : AAA.A ('A' == active, '.' == missing, 'R' == replacing)
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