Hi everyone,

I’m looking for advice on the correct recovery procedure.

My array is in a TerraMaster D4-320 USB enclosure, and Disk 3 became disabled for an unknown reason. I reseated the drive and rebooted.

The drive appears to be healthy, but Unraid will not rebuild it.

Current situation

• Unraid 7.1.4

• TerraMaster D4-320 USB enclosure

• Correct Disk 3 is detected.

• Serial number matches the original assignment.

• SMART passes with no errors.

• Disk is assigned to the correct slot.

• Array starts normally.

• Disk 3 still shows:

  Device is disabled, contents emulated

• No rebuild starts automatically.

I have not used New Config or formatted the disk because I don’t want to lose the ability to rebuild.

SMART

SMART overall health:

PASSED

Important SMART attributes:

• Reallocated Sectors = 0

• Current Pending Sectors = 0

• Offline Uncorrectable = 0

• UDMA CRC Errors = 0

SMART Error Log:

No Errors Logged

The drive appears completely healthy.

Current md status

Relevant output from mdcmd status:

mdState=STARTED

mdNumDisabled=2

mdNumInvalid=2

diskNumber.3=3

diskState.3=4

rdevStatus.3=DISK_DSBL

rdevName.3=sdc

rdevId.3=WDC_WD140EDGZ-11B1PA0_9LK9DLJG

rdevNumErrors.3=0

The physical drive is present and assigned correctly, but Unraid continues to emulate it instead of rebuilding it.

System

• Unraid 7.1.4

• Basic license

• Parity: 24 TB ST24000NM002H

• Disk 1: 8 TB WD80EFZZ

• Disk 2: 8 TB WD80EFZZ

• Disk 3: 14 TB WD140EDGZ-11B1PA0

• Cache: 500 GB NVMe

I’ve attached my diagnostics ZIP.

Could someone advise the safest procedure to clear the disabled state and get Unraid to rebuild Disk 3?

Thank you!

tower-diagnostics-20260710-0931.zip

https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/replacing-disks-in-array/#re-enabling-a-disabled-disk-rebuilding-onto-itself

You have to simulate a drive failure to trigger the rebuild

• stop array

• Unassign disk3

• Start array to make Unraid ‘forget’ current drive.

• At this point disk3 will show as being emulated. You can browse the contents of the ‘emulated’ drive to check it looks OK as what you see at this point is what will end up on the physical drive after it is rebuilt. If you do not think the contents look correct get diagnostics and then post them here to get advice on how to proceed.

• Stop array

• Assign disk3

• Start array to rebuild disk3.

Thanks! I appreciate the quick response and guidance. I’ll be able to work on the server tomorrow and will follow those steps. I’ll report back with the results.

Thank you trurl and itimpi. That procedure worked perfectly.

I followed the steps exactly:

• Unassigned Disk 3.

• Started the array so the disk was emulated.

• Verified the emulated disk contents looked correct.

• Stopped the array.

• Reassigned the same physical drive.

• Started the array again, which initiated a full rebuild onto the original drive.

The rebuild completed successfully with no errors, and all of my data appears intact.

In case it's helpful for anyone else, the drive itself appears healthy. SMART was clean before and after the rebuild (0 reallocated sectors, 0 pending sectors, 0 uncorrectable sectors, no CRC errors). The drive had simply become disabled for an unknown reason while installed in a TerraMaster D4-320 USB enclosure.

Thanks again for your help!