Trashed Raid 5 software array

Trashed Raid 5 software array

[Mark Thompson]

Hi there,

I've search low and high and havn't been able to find a solution for my
problem with a software raid that I have setup under linux.

Kernel: 2.6.6
Controller: PDC202XX (Promise TX2 ATA100 IDE Controller)

Up until recently everything was fine, but recently the array has
started playing up and dropping a disk and when I reboot the disk
doesn't have the superblock for the md device and as a result can't
start, I then explored the disk using cfdisk and the disk had no
partition there.  So I reformated and this is what I get from mdadm now:

* When I try to assemble the array manually:

cold:~# mdadm -Af /dev/md1 /dev/hd[fjl]1
mdadm: no RAID superblock on /dev/hdj1
mdadm: /dev/hdj1 has no superblock - assembly aborted


* When I assemble the array with the two disks I know work:

cold:~# mdadm -A /dev/md1 /dev/hd[fl]1
mdadm: failed to RUN_ARRAY /dev/md1: Invalid argument


* And mdadm -D

cold:~# mdadm -D /dev/md1
/dev/md1:
         Version : 00.90.01
   Creation Time : Tue May 25 14:19:54 2004
      Raid Level : raid5
     Device Size : 117218176 (111.79 GiB 120.03 GB)
    Raid Devices : 3
   Total Devices : 2
Preferred Minor : 1
     Persistence : Superblock is persistent

     Update Time : Tue Nov  2 09:18:08 2004
           State : dirty, degraded
  Active Devices : 2
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0

          Layout : left-symmetric
      Chunk Size : 32K

            UUID : 1acc6a85:ce7440d9:dfa74489:64bd5694
          Events : 0.343086

     Number   Major   Minor   RaidDevice State
        0       0        0        -      removed
        1      57       65        1      active sync   /dev/hdl1
        2      33       65        2      active sync   /dev/hdf1

It is usually a raid 5 array with 3 x 120 gig disks on it.

What I'm wanting to know, is despite the fact that hdj1 doesn't have the 
superblock is there a way I can add it to the array so that I can then 
start it and hopefuly recover the 200 gig of data on there, which I can 
then shift off to a hardware array?

RE: Trashed Raid 5 software array

[Guy]

Based on the output of mdadm -D /dev/md1...  It looks like your array is
working just fine, but missing 1 disk.  You should have access to your data
now, without any extra effort.

Since your array is running and working just fine (I hope).  Just add the
missing disk with this command.
mdadm /dev/md1 -a /dev/hdj1

You may want to test the disk first with this command.
dd if=/dev/hdj of=/dev/null bs=1024k
Note: I said test the disk, not the partition.

Any questions?  Email back before you do anything that may risk your data.

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Mark Thompson
Sent: Saturday, November 06, 2004 9:50 PM
To: Linux Raid
Subject: Trashed Raid 5 software array

Hi there,

I've search low and high and havn't been able to find a solution for my
problem with a software raid that I have setup under linux.

Kernel: 2.6.6
Controller: PDC202XX (Promise TX2 ATA100 IDE Controller)

Up until recently everything was fine, but recently the array has
started playing up and dropping a disk and when I reboot the disk
doesn't have the superblock for the md device and as a result can't
start, I then explored the disk using cfdisk and the disk had no
partition there.  So I reformated and this is what I get from mdadm now:

* When I try to assemble the array manually:

cold:~# mdadm -Af /dev/md1 /dev/hd[fjl]1
mdadm: no RAID superblock on /dev/hdj1
mdadm: /dev/hdj1 has no superblock - assembly aborted


* When I assemble the array with the two disks I know work:

cold:~# mdadm -A /dev/md1 /dev/hd[fl]1
mdadm: failed to RUN_ARRAY /dev/md1: Invalid argument


* And mdadm -D

cold:~# mdadm -D /dev/md1
/dev/md1:
         Version : 00.90.01
   Creation Time : Tue May 25 14:19:54 2004
      Raid Level : raid5
     Device Size : 117218176 (111.79 GiB 120.03 GB)
    Raid Devices : 3
   Total Devices : 2
Preferred Minor : 1
     Persistence : Superblock is persistent

     Update Time : Tue Nov  2 09:18:08 2004
           State : dirty, degraded
  Active Devices : 2
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0

          Layout : left-symmetric
      Chunk Size : 32K

            UUID : 1acc6a85:ce7440d9:dfa74489:64bd5694
          Events : 0.343086

     Number   Major   Minor   RaidDevice State
        0       0        0        -      removed
        1      57       65        1      active sync   /dev/hdl1
        2      33       65        2      active sync   /dev/hdf1

It is usually a raid 5 array with 3 x 120 gig disks on it.

What I'm wanting to know, is despite the fact that hdj1 doesn't have the 
superblock is there a way I can add it to the array so that I can then 
start it and hopefuly recover the 200 gig of data on there, which I can 
then shift off to a hardware array?
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