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 Post subject: Trouble repurposing MyCloud drives
PostPosted: January 5th, 2023, 10:25 
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Joined: January 5th, 2023, 10:22
Posts: 2
Location: United States
Hi,

I recently bought a WD MyCloud EX2 Ultra that was advertised as 8TB with the intent of setting it up as an 8TB RAID1 unit. Unfortunately, after receiving it I discovered that the "8TB" meant "8TB striped" (RAID0) and the 2 drives inside were only 4TB. So I replaced the two 4TB with 8TB drives, and successfully created an 8TB RAID1 array with those.

Now I would like to use the two 4TB drives as normal hard drives, but I can't get either of them to format. They will not format under Linux (error reading sector 0); I've also tried other disk utilties and they both always fail with various errors.

When I research the various errors I'm seeing, I see a lot of people stating the disks are bad and need to be replaced. But I'm not sure I believe that because:

1. No matter what tool/command I use, both drives give exactly the same errors. It's hard to believe they both failed in exactly the same way.

2. The drives are literally brand new...again, hard to believe they're both bad.

3. I ran gsmartcontrol on both drives with all available tests and they both had no errors.

I ran "hdparm -I /dev/sdX" against both drives and they both show as "locked". I'm not sure what that means but I can't help but wonder if this might be the problem.

Appreciate any help, thanks.


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 Post subject: Re: Trouble repurposing MyCloud drives
PostPosted: January 18th, 2023, 13:15 
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Joined: January 5th, 2023, 10:22
Posts: 2
Location: United States
OK, I managed to figure out how to do this. Luckily, I had an old 3ware RAID controller card which I used in a Ubuntu system. Here is the procedure I used:

1. Installed the RAID card and connected both drives to it.
2. Powered on the machine and entered the cards BIOS
3. The card BIOS saw both drives as 1.6TB drives instead of 4TB. I ignored this for now.
4. Created a RAID1 (mirror) array, then exited the card BIOS
5. Started Ubuntu. It saw the array as a single device (/dev/sdb)
6. Formatted /dev/sdb as ext4 and mounted it
7. Tested by going to the mount directory, creating, editing and deleting a file. Looked good.
8. Rebooted the machine and entered the card BIOS again.
9. Deleted the RAID1 array.
10. Powered down the system completely. Disconnected both drives from the card.
11. Connected one of the drives to the motherboard.
12. Restarted Ubuntu. It now saw the single drive as an ext4 partition.
13. Started the gnome-disks app ("Activities->disk->Disks")
14. Saw the drive listed. It showed about half of the space used (a lie).
15. Selected the drive and chose "Format Partition". Selected "ext4".
16. Selected "Edit Mount Info" in Disks. Deselected "mount at startup" and entered a mount point
17. Clicked the "Play Button" to mount the drive. It now showed only around 1% used instead of about 55%.
18. Exited Disks.
19. Went to the mount point and tested as in 7. above

Disk recovered!


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 Post subject: Re: Trouble repurposing MyCloud drives
PostPosted: January 18th, 2023, 16:02 
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Joined: September 8th, 2009, 18:21
Posts: 15461
Location: Australia
Your RAID card has a 32-bit LBA limitation.

https://www.google.com/search?q=4+TB+-+2+TiB+in+TiB

    4TB - 2TiB = 1.64 TiB

I would be concerned as to what would happen when you try to write data beyond the 1.64 TiB point. Would it wrap around to LBA 0?

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A backup a day keeps DR away.


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