Hey everyone! Would appreciate some guidance here, as I'm at a loss.

I was out of town for a few weeks and came back to 2 drives 'Device is Disabled, Content Emulated'. Luckily I have 2 parity drives. I ran SMART tests on the drives, everything seems fine. I shutdown my server, I took them out and put them back into their drive bays, booted the server, then stop the server, removed the drives from the array, started the server in maintenance mode, then shutdown the server again, added the drives back into the array, and booted up the server again. The data rebuild started - great.

About 40% of the way through - the data rebuild stops/fails. It also kicks out multiple drives into Unassigned Devices. They now show with a * temperature, and throw disk errors during data rebuild. This is for both the drives being rebuilt, parity, and other random drives. Also, my 'appdata' and 'system' shares disappeared.

This whole process has happened 3 times now - and I'm at a loss of what to do to properly rebuild the data disk. What's worse is it takes days to hit the issue due to rebuilding 20TB at 60MB/s. Please help!

diagnostics-20260111-1235.zip

Edited January 11Jan 11 by Boy Kai

Probably a power issue with so many drives. What is the exact model of your PSU? How are the drives connected to power?

Ideally no more 4 drives per PSU cable. MOLEX-SATA power splitters are better than SATA-SATA power splitters.

36 minutes ago, trurl said:

Probably a power issue with so many drives. What is the exact model of your PSU? How are the drives connected to power?

Ideally no more 4 drives per PSU cable. MOLEX-SATA power splitters are better than SATA-SATA power splitters.

14 of the drives are on these:

https://www.amazon.com/dp/B07Y4F5SCK

• 9 drives

https://www.amazon.com/dp/B09TV1XPDD

• 5 drives

The rests are in the actual PC case. Which are powered with a 850W PSU.

• 8 drives

USB not recommended for assigned disks for many reasons.

I've had this setup for a couple years. Not sure how this is related to the new issues I've been having. Would appreciate some guidance.

I plan on upgrading my server but right now prices are insane. Would like to resolve without having to get a 4U setup.

Edited January 11Jan 11 by Boy Kai

Multiple USB devices disconnecting:

Jan 10 22:31:25 LaughingMan kernel: usb 2-2.4.2: USB disconnect, device number 6

Jan 10 22:31:25 LaughingMan kernel: md: disk9 read error, sector=17270386128

Jan 10 22:31:25 LaughingMan kernel: usb 2-2.4.3: USB disconnect, device number 8

Jan 10 22:31:25 LaughingMan kernel: usb 2-2.4.3.1: USB disconnect, device number 13

Jan 10 22:31:26 LaughingMan kernel: md: disk17 read error, sector=17270393040

Jan 10 22:31:26 LaughingMan kernel: md: disk8 read error, sector=17270393040

Jan 10 22:31:26 LaughingMan kernel: usb 2-2.4.3.4: USB disconnect, device number 21

Jan 10 22:31:26 LaughingMan kernel: md: disk20 write error, sector=17270385104

So more disks are disabled, then parity can emulate, as mentioned USB is not recommended, but you can try a different USB port/controller, then post new diags after array start.

5 hours ago, JorgeB said:

Multiple USB devices disconnecting:

Jan 10 22:31:25 LaughingMan kernel: usb 2-2.4.2: USB disconnect, device number 6

Jan 10 22:31:25 LaughingMan kernel: md: disk9 read error, sector=17270386128

Jan 10 22:31:25 LaughingMan kernel: usb 2-2.4.3: USB disconnect, device number 8

Jan 10 22:31:25 LaughingMan kernel: usb 2-2.4.3.1: USB disconnect, device number 13

Jan 10 22:31:26 LaughingMan kernel: md: disk17 read error, sector=17270393040

Jan 10 22:31:26 LaughingMan kernel: md: disk8 read error, sector=17270393040

Jan 10 22:31:26 LaughingMan kernel: usb 2-2.4.3.4: USB disconnect, device number 21

Jan 10 22:31:26 LaughingMan kernel: md: disk20 write error, sector=17270385104

So more disks are disabled, then parity can emulate, as mentioned USB is not recommended, but you can try a different USB port/controller, then post new diags after array start.

Thanks! I'll give it a try.

Rebuilding 1 disk at a time and swapping USB ports.

On 1/12/2026 at 9:31 AM, Boy Kai said:

Thanks! I'll give it a try.

Rebuilding 1 disk at a time and swapping USB ports.

Unfortunately this failed again. It always fails around 35 - 40%. Not sure why or what to do to resolve.

diagnostics-20260113-2112.zip

41 minutes ago, Boy Kai said:

Not sure why

On 1/12/2026 at 3:30 AM, JorgeB said:

Multiple USB devices disconnecting

42 minutes ago, Boy Kai said:

what to do to resolve

On 1/11/2026 at 2:07 PM, trurl said:

USB not recommended for assigned disks for many reasons.

Yep, still a USB issue, disks are dropping offline.

I totally get USB is not recommended. I just don't have the money to buy a 4U setup right now to run them through SATA.

I am a bit confused why the rebuild runs for ~8TB but fails at 30-40% for a 20TB rebuild. Also confused why the USB setup has been working for the past 2 years but is now facing issues.

Is there something I can do without buying completely new hardware to address the disabled disk issues I'm facing currently?

If you run without parity no disk can become disabled since there is nothing for the array to be in sync with. But of course, you can't rebuild anything either.

1 hour ago, trurl said:

If you run without parity no disk can become disabled since there is nothing for the array to be in sync with. But of course, you can't rebuild anything either.

Thanks!

If I stop the array and remove parity disk then start the array

Will the 2 disabled disks become available as-is with their existing data on them? I'd assume, if I add parity drives back later - it will rebuild the array to update the parity sync?

You will have to do New Config to enable the disabled disks and you can unassign both parity at that time. The 2 disabled disks will become available as they were when they became disabled. Any writes to those disks after they became disabled would only have updated parity so you could rebuild them from parity. Some possibility they would be unmountable if filesystem wasn't completely updated at that time, but could probably be repaired with check filesystem in that case.

10 minutes ago, Boy Kai said:

if I add parity drives back later - it will rebuild the array to update the parity sync?

When you assign parity and start the array, parity will be built based on the contents of the data disks at that time. Assuming it can build parity.

This is super helpful! Thank you so much. I'll give it a try.