Disk disabled, in error. How to fix?

[Dundee]

One of my disk is in error.

I wanted to provide self-test results, but i cant run the test

When i click on START for the short or long test, the button changes to STOP for 0.1s and then reverts back to START as it was before, while the button for the other test becomes disabled.

 

unraidnas-diagnostics-20240809-1209.zip

Edited August 9 by Dundee
Added diagnostics

[JorgeB]

Please post the diagnostics.
 

[Dundee]

Added diagnostics

[itimpi]

Looks as if disk2 dropped offline which explains why SMART information is not available.  Check that the power and SATA cabling to the drive is firmly seated.  You will need to reboot (and possibly even power-cycle) the server to get that drive back online so its SMART information can be obtained.

[Dundee]

 

Smart Test results (short): Completed without error

The disk is now unassigned and when i try to assign it as Disk2 as before, its seems to be detected as a new disk and Unraid wants to rebuild it

 

 

 

WDC_WD101EFBX-68B0AN0_VHGGHY6M-20240809-1146.txt

Edited August 9 by Dundee
Fixed Smart report

[JorgeB]

11 minutes ago, Dundee said:

its seems to be detected as a new disk and Unraid wants to rebuild it

That's expected, but before doing that make sure the emulated disk is mounting, by starting the array without that disk assigned.

 

The SMART report you posted is incomplete, try again.

[Dundee]

 Sorry, smart report fixed in previous post.

Array started with the disk unnassigned, this is what i see.

 

Why would the disk have to be completly rebuilt?

 

[JorgeB]

SMART looks fine, couple of UDMA CRC errors, so replace the SATA cable, and since the emulated disk is mounting you can rebuild on top

[Dundee]

Last questions, i hope

- Replace the SATA cable? Do you mean make sure its in place or change it?

- So i need to stop the array, assign the drive as disk2 as previously, and start the array? And the drive will be rebuilt?

- Why does the drive need to be rebuilt? The data is all there....

 

[JonathanM]

4 minutes ago, Dundee said:

Why does the drive need to be rebuilt? The data is all there

Where do you think the data is currently?

[trurl]

1 hour ago, Dundee said:

Why does the drive need to be rebuilt? The data is all there....

The disk was disabled because a write to it failed. After a disk is disabled, it is not used again until rebuilt. Instead, the disk is emulated by the rest of the array. Any reads from the emulated disk actually read all other disks and get the data from the parity calculation. Any writes to the emulated disk update parity as if the disk were written. The initial failed write, and any subsequent writes to the emulated disk, can be recovered by rebuilding.

1 hour ago, JonathanM said:

Where do you think the data is currently?

The answer is the data is actually being emulated by the array and any data you see is the result of the emulation.

 

Also, the disk needs to be rebuilt because the missed writes means it is out-of-sync with the array.

 

The only other way to get the array back in sync is New Config and rebuild parity. But any emulated writes would be lost. And possibly some of the missed writes could make the filesystem corrupt.

 

So rebuilding the data disk is exactly what you want to do.

[Dundee]

Thanks for the explanation Trurl!