2Big Lacie lost its raid settings

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Videodrone
Posts: 21
Joined: Sun Jul 05, 2009 7:05 pm

2Big Lacie lost its raid settings

Post by Videodrone » Sun Jul 26, 2009 6:29 pm

Hello.

Whilst trying to upgrade my 2TB Lacie with 2 x 1.5TB drives I have managed to loose the raid settings. Not sure if these are in firmware or on the disks. So I can connect to the 2Big but under "System" , "Disk" it shows no disk size or raid information. Does anyone know how to recover from this ? For example which file the raid settings are held ?

For information, the following caused the problem. I copied the partition table, and each partition across to 2 new discs with sfdisk and dd. Put the new drives in the 2Big and turned it on. Blue light so thought it was OK. Logged on OK but saw there were no raid settings. So put old disks back in and turned it on. Now got no raid settings in the old disks either.

any ideas ?

regards
...drone

Mijzelf
Posts: 6207
Joined: Mon Jun 16, 2008 10:45 am

Re: 2Big Lacie lost its raid settings

Post by Mijzelf » Mon Jul 27, 2009 1:52 pm

Did you reinstall the disks in the same order? This could be important.

When it's standard software raid, the raidsettings are in /etc/mdadm.conf. The contents should be something like

DEVICE /dev/sda5 /dev/sdb5

when sda5 and sdb5 contain the userdata.

Videodrone
Posts: 21
Joined: Sun Jul 05, 2009 7:05 pm

Re: 2Big Lacie lost its raid settings

Post by Videodrone » Mon Jul 27, 2009 6:30 pm

Hello mijzelf.

Regarding LH and RH drives. Using my other (working) 2-Big Lacie, I tried swapping the Left Hand drive with the Right hand drive and the Lacie works fine. Seems it does not care which bays the two drives are put. There was indeed a text file in /etc that looks as you suggest.

Meanwhile. . . . .

I looked at the log for the "dead" Lacie and it goes wonky at the point below. The drive is called "LaCie-New"

Question.

Whats a "superblock" ?

Jul 27 17:06:59 LaCie-New local1.notice mountuserfs: mdadm: No md superblock detected on /dev/sda2.
Jul 27 17:06:59 LaCie-New local1.notice mountuserfs: mdadm: No md superblock detected on /dev/sdb2.
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs: mdadm: No md superblock detected on /dev/sda2.
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs: mdadm: No md superblock detected on /dev/sdb2.
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs: Failure: Could not start md4
Jul 27 17:07:00 LaCie-New user.warn kernel: XFS: SB read failed
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs: mount:
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs: mounting /dev/md4 on /home failed
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs:
Jul 27 17:07:00 LaCie-New local1.notice mountuserfs: WARNING, failed to mount
Jul 27 17:07:00 LaCie-New local1.notice InitNG: Service mountuserfs is up.
Jul 27 17:07:00 LaCie-New local1.notice InitNG: Service mdadm is up.

regards
Shaun

Mijzelf
Posts: 6207
Joined: Mon Jun 16, 2008 10:45 am

Re: 2Big Lacie lost its raid settings

Post by Mijzelf » Tue Jul 28, 2009 5:35 pm

A superblock is a block of metadata descibing a filesystem.

For some reason the descriptor of the raid device is broken.

Does the userdata partition contain any important data? If not, and if you can open a shell you can re-create the raid device.

Code: Select all

#create the raidarray
mdadm --create /dev/md4 --level=raid0 --raid-devices=2 /dev/sda2 /dev/sdb2
#assemble the raidarray
mdadm --assemble /dev/md4 /dev/sda2 /dev/sdb2
#create a filesystem
/sbin/mkfs.xfs /dev/md4
#mount it
mount /dev/md4 /home
use --level=raid0 for striping (raid device is twice the size of a data partition) and --level=raid1 for mirroring (raid device is redundant)

Videodrone
Posts: 21
Joined: Sun Jul 05, 2009 7:05 pm

Re: 2Big Lacie lost its raid settings

Post by Videodrone » Tue Jul 28, 2009 6:24 pm

Thanks Mijzelf.

To be clear before I try this, my Lacie was set for "concatenated" so the 2 x 1TB drives appeared as one big 2TB drive. I assume I use raid 0 yes ?

Also.
I assumed the Lacie would sort out its own formatting of the "concatenated" partition being sdb2 and sdc2. Perhaps it doesn't. Perhaps I need to copy images from each of sdb2 and sdc2 onto the new drives to get it to work. Maybe this is why it cannot find a superblock.

Also.
Trawling about on the net, it seems the Lacie 2-Big might store some files on the "concatenated" raid "drive" itself, apparently a directory called "public" with several sub directories. When I reconstructed my drives from the backup partition table and partition images with sfdisk and dd, I did not copy anything onto the partitions /dev/sdb2, or /dev/sdc2, which are the two partitions that "add together" to make the raid drive. So my Lacie must be missing these extra files that may or may not reside on the raid-0 drive.

Question.
Do raid devices normally store "system type" files on the joined-together-partition ? apart from user files like music and video I mean. Or is the Lacie doing something unusual in keeping some of its own files there ? (assuming it does, even . . .)

My intent is to use your suggestion on my older (working) drive to see if I can find any odd files on it. I will take images from it first. . . .

regards
...drone

Mijzelf
Posts: 6207
Joined: Mon Jun 16, 2008 10:45 am

Re: 2Big Lacie lost its raid settings

Post by Mijzelf » Wed Jul 29, 2009 6:37 am

my Lacie was set for "concatenated" so the 2 x 1TB drives appeared as one big 2TB drive. I assume I use raid 0 yes ?
I assume so, however, the name 'concatenated' could also mean JBOD (--level=linear).
So my Lacie must be missing these extra files that may or may not reside on the raid-0 drive.
Could be. But your log mentions an error in an earlier stage. The array can't be assembled, so the contents is of course unreadable.
Do raid devices normally store "system type" files on the joined-together-partition ?
No. The raiddevice creates a new device, /dev/mdx which, apart from the name, can't be distinguished from any other blockdevice. That's why you can put any filesystem on it, the raid manager doesn't need to know it.
I assumed the Lacie would sort out its own formatting of the "concatenated" partition being sdb2 and sdc2. Perhaps it doesn't.
That could be very true. Since Lacie only supports pre-formatted disks, they don't need to support autodetection of unformatted partitions.

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