how to restore superblock for raid?

richis · n00b Joined: 10 Feb 2004 Posts: 20

Hi,

I have messed up with my software raid. After trying to fix some problems I entered such commands:
mdadm --zero-superblock /dev/hdc1
mdadm --zero-superblock /dev/hdb1

Is there any way to restore superblocks? (badly need data from raid)

before problem I used raid-tools and here is config:
/etc/raidtab

NeddySeagoon · Posted: Tue Aug 08, 2006 2:31 pm Post subject:

richis.

A persistant superblock is not required to read the raid.
Since you used raidtools, sitch with it, don't mix and match.

Does

richis · n00b Joined: 10 Feb 2004 Posts: 20

raidstart /dev/md0
/dev/md0: Invalid argument

here is log from dmesg:

NeddySeagoon · Posted: Tue Aug 08, 2006 4:39 pm Post subject:

richis,

Edit your raidtab, change persistent-superblock 1 to persistent-superblock 0 and try again.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

richis · n00b Joined: 10 Feb 2004 Posts: 20

already did, still the same

BlinkEye · Posted: Fri Aug 11, 2006 12:12 am Post subject:

does

richis · n00b Joined: 10 Feb 2004 Posts: 20

/dev/md0 is still there =)

I think I have done some bigger mistake. In smoe forums I found that I have to recreate partition table on disks.
And I have done fdisk on both disks (removed partitions and created them).

Is this end of my data on disk? =(

NeddySeagoon · Posted: Sun Aug 13, 2006 8:50 am Post subject:

richis,

Provided you only changed the partition table for primary partitions, you can change it as much as you like, as long as you put it back the way it was, you data is still there.

Its more complex with the extended and logical partitions, since every time they are created or destroyed, one sector is written to the disk.
Overwriting what is there, with the same partition information is harmless. Changes will begin to destroy your data.

Get testdisk and scan for partitions - you may be lucky.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

richis · n00b Joined: 10 Feb 2004 Posts: 20

thanks for tool name, but still problem with testdisk.

here is report. Any other way to recover this "big" partition?

NeddySeagoon · Posted: Sun Aug 13, 2006 5:32 pm Post subject:

richis,

If the disk was given over to a single primary partition, using all the space, simply recreate it with fdisk and everything comes back. Even if it wasn't, you can always get the first primary partition back that way, which looks good for /dev/hdc1 etc.

If you do that and there were further partitions, make sure any mounts you attempt are read only.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.