[SOLVED] Unable to mount former RAID hard drive

jbruyet · 11-01-2014, 10:52 AM

Hey all, I had a Linux server (white box) that had two 1TB hard drives in a RAID1 array. The motherboard went out (blown caps) so I scrounged the parts and set them on a shelf. I needed additional disk space in my OpenSUSE workstation so I took one of the drives and installed it. When I ran fdisk -l I saw the drive under /dev/sdc and /dev/sdc1 but I also saw it under /dev/md127 (the old array). I used fdisk to remove partitions and made a new partition of type 83 and using the entire disk but no joy; /dev/md127 is still there. I Googled this problem and as a fix I ran:

Code:

dd if=/dev/urandom of=/dev/sdc bs=1M

I rebooted my computer, ran fdisk -l again and all I saw was /dev/sdc. Yes! Well, no. I created a new partition on /dev/sdc and while I now have /dev/sdc1 I also have /dev/md127 again. I tried to mount /dev/sdc1 and I get this error:

Code:

linux-b8kj:/home/jobee # mount /dev/sdc1 /mnt/temp
mount: unknown filesystem type 'linux_raid_member'
linux-b8kj:/home/jobee #

I even tried mounting /dev/md127; at least it's a different error:

Code:

linux-b8kj:/home/jobee # mount /dev/md127 /mnt/temp
mount: /dev/md127 is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/md127,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.
linux-b8kj:/home/jobee #

Any ideas on what I can do to return this hard drive to a mountable state?

Thanks,

Joe B

jbruyet · 11-01-2014, 10:59 AM

Ok, I just found this:

Quote:

The simplest way to access that data is to assemble the raid device. In a RAID-1 volume, a single device is sufficient.

madadm -A /dev/sdc1

but when I run it I get this:

Code:

linux-b8kj:/home/jobee # mdadm -A /dev/sdc1
mdadm: device /dev/sdc1 exists but is not an md array.
linux-b8kj:/home/jobee #

I'm going to go do something else and check back here later...

Thanks,

Joe B

dalai lama · 11-02-2014, 07:12 AM

Hi Joe,

What is it exactly now you are trying to do? First you dd'd the disk and after that you are trying to activate the mdadm partition?
Does cat /proc/mdstat stil list the partition on the disk? What does mdadm.conf say? Does it list the hard disk as a software raid device? If so you will need to remove it first with -f and -r option.

Robert

michaelk · 11-02-2014, 08:21 AM

I would guess that mdadm is trying to rebuild the array. Try this:

mdadm --stop /dev/md127
mdadm --zero-superblock /dev/sdc (Verify you are using the correct device ID)

jbruyet · 11-19-2014, 02:14 PM

Sorry for the slow responses; it's been pretty busy here. On a lighter note, my 2015 budget was approved in entirety.

dalai lama,

Quote:

What is it exactly now you are trying to do?

All I'm trying to do is get this 1TB hard drive in a condition where it can be used in my workstation (OpenSUSE 13.1)

Quote:

First you dd'd the disk and after that you are trying to activate the mdadm partition?

I did the dd thinking that would erase whatever is left on it that's preventing me from using the drive. The part about creating a one-drive array was something I read that was supposed to fix the problem

Quote:

Does cat /proc/mdstat stil list the partition on the disk?

Code:

linux-b8kj:/home/jobee # cat /proc/mdstat
Personalities : [raid1] 
unused devices: <none>
linux-b8kj:/home/jobee #

Quote:

What does mdadm.conf say?

Code:

linux-b8kj:/home/jobee # find / -iname mdadm.conf
find: ‘/var/run/user/1000/gvfs’: Permission denied
find: ‘/run/user/1000/gvfs’: Permission denied
linux-b8kj:/home/jobee #

Quote:

Does it list the hard disk as a software raid device? If so you will need to remove it first with -f and -r option.

See above

michaelk, I was able to run the stop command with no errors but the zero command, not so much:

Code:

linux-b8kj:/home/jobee # mdadm --zero-superblock /dev/sdc
mdadm: Unrecognised md component device - /dev/sdc
linux-b8kj:/home/jobee #

And sdc is the correct drive. Is there no way to just blank this drive so I can use it for other purposes?

Thanks,

Joe B

michaelk · 11-19-2014, 07:31 PM

Post the output of
mdadm --examine --verbose --scan

jbruyet · 11-21-2014, 05:59 PM

michaelk, here's the output:

Code:

linux-b8kj:/home/jobee # mdadm --examine --verbose --scan
ARRAY /dev/md/0  level=raid1 metadata=1.2 num-devices=2 UUID=0fd71104:ab49def8:8ea16fc2:9bbff84e name=srvBackup:0
   devices=/dev/sdc1
linux-b8kj:/home/jobee #

Yep, srv-Backup is the server the drives came out of. I saw the /dev/md/0 so I took a look there. Here's what I saw:

Code:

linux-b8kj:/dev/md # ls -l
total 0
lrwxrwxrwx 1 root root 8 Nov 21 15:43 srvBackup:0 -> ../md127
linux-b8kj:/dev/md #

All this yatta yatta from installing one hard drive in my computer. Yow.

Thanks,

Joe B

michaelk · 11-21-2014, 06:38 PM

So try zeroing sdc1 vs sdc

jlinkels · 11-21-2014, 08:37 PM

Really, it is very hard to nuke a mdadm array beyond repair.

I tried it as well for testing a backup procedure and it is really hard.

I am wondering something. You issued the dd command from /dev/random with a BS of 1M. This drive is 1 TB. That should have taken hours if not days to complete. First it is 1,000,000 blocks, secondly you asked for 10e9 random numbers. I didn't you hear complaining about it. So I really doubt if the writing was completed correctly.

My favorite way of nuking mdadm arrays:

Code:

dd if=/dev/zero of=/dev/sdc BS=100M

At the end you should see that about 1,000,000,000,000 bytes have been written. A bit more because of the 1024x1024x1024... yada yada.

Once you have seen that it is unlikely that the array survived that.

jlinkels

jbruyet · 11-24-2014, 11:46 AM

--> michaelk,

Code:

linux-b8kj:/home/jobee # mdadm --zero-superblock /dev/sdc1
mdadm: Couldn't open /dev/sdc1 for write - not zeroing
linux-b8kj:/home/jobee #

--> jlinkels, I will redo the dd per your parameters.

Thanks for the help,

Joe B

jbruyet · 11-24-2014, 05:14 PM

Thank you jlinkels:

Code:

linux-b8kj:/mnt/stuff/Test # ls -l
total 4
-rw-r--r-- 1 root root 29 Nov 24 15:13 hello.txt
linux-b8kj:/mnt/stuff/Test # cat hello.txt
This is only a test. Honest. linux-b8kj:/mnt/stuff/Test # 
linux-b8kj:/mnt/stuff/Test #

Looks like I can mount the drive, create folders and files and edit them.

Thanks again,

Joe B

Soapm · 11-24-2014, 07:16 PM

if you're trying to use the drive, no need doing the dd... that will take forever. Just create a new filesystem and it will overwrite the drive.

mkfs.ext4 /dev/sdc1

You may have to firse it if it see's the superblock. I think the force switch is -f