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mohtasham1983

Member

Registered: 2008-12-15

Posts: 85

Recovering RAID 5 data from a different computer

I made a huge mistake and created a software based RAID 5 using three hard drives 7 years ago on my old desktop computer that was running on Arch Linux. Back then I had too much time. Unfortunately I can no longer start my old computer after it was in closet for 6 years. So tonight I removed the hard drive from my old computer and connected it to my new computer, which also runs on Arch linux, I was able to copy mdam.conf-backup to my new computer. Since I only have two extra Sata cables, I connected two out of the three hard drives that were part of the old RAID array to my new computer and started it. However, I'm not too sure if it's possible to reconstruct my RAID array on the new computer while one disk is missing.

Here's the output for fdisk:

sudo fdisk -l
Disk /dev/sdb: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: WDC WD20EZRX-00D
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 38746435-BF3B-45B3-B6E8-B36AB9BEE740

Device     Start        End    Sectors  Size Type
/dev/sdb1   2048 3907028991 3907026944  1.8T Microsoft basic data


Disk /dev/sdc: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: WDC WD20EZRX-00D
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 75DDA84A-94DD-41A3-AEB9-001CDE537726

Device     Start        End    Sectors  Size Type
/dev/sdc1   2048 3907028991 3907026944  1.8T Microsoft basic data

And here's the content of my old mdmd.conf:

ARRAY /dev/md/first metadata=1.2 name=localhost:first UUID=b42fd0a2:eb030310:501566ab:d8869db8

I kept hard drives unmounted and ran:

sudo mdadm --assemble --scan -c ~/tmp/raid/mdam.conf-backup

But it returned no output. Although, the above command's returned error code #2, which I believe is returned when no file or directory is found. I ran the command after creating "/dev/md/first" too, but got the same error.

Any idea how I should recover my data? I don't remember anything about what I did 7 years ago and I'm afraid to erase my data if I run a command by mistake.

frostschutz

Member

Registered: 2013-11-15

Posts: 1,652

Re: Recovering RAID 5 data from a different computer

mdadm --examine /dev/sd*?

in the config file, remove name= metadata=, just use the UUID as only criteria nothing else

Last edited by frostschutz (2020-10-25 11:07:03)

mohtasham1983

Member

Registered: 2008-12-15

Posts: 85

Re: Recovering RAID 5 data from a different computer

The output of examine command:

sudo mdadm --examine /dev/sd*                       
/dev/sda:
   MBR Magic : aa55
Partition[0] :    488397167 sectors at            1 (type ee)
/dev/sda1:
   MBR Magic : aa55
mdadm: No md superblock detected on /dev/sda2.
/dev/sdb:
   MBR Magic : aa55
Partition[0] :   3907029167 sectors at            1 (type ee)
mdadm: No md superblock detected on /dev/sdb1.
/dev/sdc:
   MBR Magic : aa55
Partition[0] :   3907029167 sectors at            1 (type ee)
mdadm: No md superblock detected on /dev/sdc1.

It looks like my hard drives don't even look like they were part of a raid array

I removed both name= metadata= but I got the same error code 2 after running:

sudo mdadm --assemble --scan -c ~/tmp/raid/mdadm.conf-bak

Note that I created a new conf file based on your suggestion to remove name and metadata from it.

Last edited by mohtasham1983 (2020-10-25 11:37:59)