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Disk failed - replacement disk showing unRAID's signature on the MBR failed

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A couple of days ago a disk in my server showed a red cross. I bought a new disk which I have added. When I go to pre-clear the disk though it started running for an hour or so and then showed the error 'UnRAID's signature on the MBR failed - Aborted'. The new disk is still showing in the unassigned devices list, but when I go to the preclear tool it says no unassigned disks available?


Any help appreciated. I attached the diagnostics that I took yesterday (I had to do a reboot to run the pre-clear).



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Thanks Trurl, I thought that earlier and checked and couldnt see anything obvious loose. I will open up and double check again. Anything else it could be or anything else I could try?

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Could be:

- Loose SATA/SAS connection on drive side (to drive or drive cage)

- Loose SATA/SAS connection on controller side

- Drive not inserted fully into drive cage

- Bad cable

- Bad cage

- Bad drive (unlikely)


It takes very little for a connection to become intermittent - a tiny skew would be enough, caused by just brushing your hand across the cable when installing a different drive or doing other maintenance. Locking calbes help, but are not infallible.


Drive cages that allow disks to be swapped without opening the case are the preferred way to go. And when burning in a server, it is good to test out all of the drive slots, not just the ones you are using initially.

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Ok, so had a look and couldnt see anything obviously loose. Restarted and found the disk fine and started pre-clear, after a couple of hours though it has aborted and the disk is no longer showing in the unassigned disks list.


I'm going to order a new Sata cable and see if that resolves

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Looks like sdf is the unassigned drive:

Serial Number:    WD-WCC4N5UDYRA8
  5 Reallocated_Sector_Ct   0x0033   169   169   140    Pre-fail  Always       -       926
196 Reallocated_Event_Count 0x0032   195   195   000    Old_age   Always       -       5
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       1

Don't use it!

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