Cannot re-create software raid

BinWondrin · 01-19-2009, 12:19 AM

I am tearing my hair out!

I rebuilt a system that had a raid-1 software raid setup.
I had lvm2 on top of the software raid-1 on the old system.
For the rebuilt system I decided to go without lvm on the raid-1 disk.

I seem to have remnants of the old superblocks on one of the drives. I tried to zerodisk the hard drives. I re-partitioned them and whatnot.

Here is some of the relevant info:

Code:

[root@acoustix ~]# mdadm --detail md0
mdadm: cannot open md0: No such file or directory

and ...

Code:

[root@acoustix ~]# fdisk -l

Disk /dev/sda: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0000a6f0

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          25      200781   83  Linux
/dev/sda2              26       48641   390508020   8e  Linux LVM

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000376ac

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      121601   976760001   fd  Linux raid autodetect

Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0003478f

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1      121601   976760001   fd  Linux raid autodetect

and...

Code:

[root@acoustix ~]# mdadm --examine /dev/sdb1
/dev/sdb1:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : ee0b6cb3:85affa5d:0a205f1d:b371822a
  Creation Time : Sun Jan 18 20:52:02 2009
     Raid Level : raid1
  Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
     Array Size : 976759936 (931.51 GiB 1000.20 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0

    Update Time : Sun Jan 18 20:55:09 2009
          State : active
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
       Checksum : aa070f11 - correct
         Events : 5


      Number   Major   Minor   RaidDevice State
this     0       8       17        0      active sync   /dev/sdb1

   0     0       8       17        0      active sync   /dev/sdb1
   1     1       8       33        1      active sync   /dev/sdc1


Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0003478f

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1      121601   976760001   fd  Linux raid autodetect

and ...

Code:

[root@acoustix ~]# mdadm --examine /dev/sdc1
mdadm: No md superblock detected on /dev/sdc1.

and finally:

Code:

[root@acoustix ~]# mdadm --zero-superblock /dev/sdb1
mdadm: Couldn't open /dev/sdb1 for write - not zeroing

Do I have to wipe /dev/sdb completely to be able to reuse it?
How should I wipe it? dd /dev/zero? This is a 1 terabyte drive. Could take a while.

Any help is appreciated. Sorry for the longish post.

BinWondrin
:-)

centos82 · 01-19-2009, 12:43 AM

Run "fdisk /dev/sdb"

If you want /dev/sdb1 to be a partition for an ext2/3 filesystem:
At prompt type: t
At prompt type: 1
At prompt type: 83

If you want /dev/sdb1 to be a prtition usable with LVM:
At prompt type: t
At prompt type: 1
At prompt type: 8e

To finalize the changes at the prompt type "w" and hit enter.

BinWondrin · 01-19-2009, 12:15 PM

Sorry CentOS82,
I guess I didn't explain myself properly. I used fdisk on the 2 drives several times switching it back and forth between type 82 and fd but to no avail. I still couldn't add both devices to the software raid-1 array.

BinWondrin

rayfordj · 01-19-2009, 12:23 PM

BinWondrin,

What does 'cat /proc/mdstat' currently report?

BinWondrin · 01-19-2009, 04:00 PM

[root@acoustix ~]# cat /proc/mdstat
Personalities :
md_d0 : inactive sdb1[0](S)
976759936 blocks

unused devices: <none>