Hello,

I got a used 6TB drive I intended to use for my parity drive. I replaced my existing 4TB parity drive and rebuilt parity. Now, when I stop my array to swap the old 4TB parity drive into my data array, my new parity drive is marked as missing. I haven't had to debug a drive issue since I started using Unraid, so I was hoping that someone could help me out. I see the following in the SYSLOG and have shared the full diagnostics if they are useful.

SYSLOG snippet about the drive mounting:

Aug 29 12:33:39 Evergreen webgui: Successful login user root from 192.168.68.64
Aug 29 12:36:17 Evergreen emhttpd: online: ST6000VX009-2ZR186_ZVY0AYP6 (sdc) 512 11721045168 => MBR read error
Aug 29 12:36:17 Evergreen kernel: usb 4-1.3: USB disconnect, device number 5
Aug 29 12:36:17 Evergreen kernel: sd 3:0:0:0: [sdc] tag#14 uas_zap_pending 0 uas-tag 1 inflight: CMD 
Aug 29 12:36:17 Evergreen kernel: sd 3:0:0:0: [sdc] tag#14 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 00 00 00 00 20 00 00
Aug 29 12:36:17 Evergreen kernel: sd 3:0:0:0: [sdc] tag#14 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=DRIVER_OK cmd_age=0s
Aug 29 12:36:17 Evergreen kernel: sd 3:0:0:0: [sdc] tag#14 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 00 00 00 00 20 00 00
Aug 29 12:36:17 Evergreen kernel: I/O error, dev sdc, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2
Aug 29 12:36:17 Evergreen kernel: device offline error, dev sdc, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Aug 29 12:36:17 Evergreen kernel: Buffer I/O error on dev sdc, logical block 0, async page read

Any help or advice would be appreciated.

Thanks,

Hunter.

evergreen-diagnostics-20260829-1237.zip

Edited Saturday at 04:48 PM3 days by Hunter M
added screenshot of main tab

check the cables (power and data) and/or swap them with another disk and see if problem follows or stays with same disk.

5 minutes ago, MowMdown said:

check the cables (power and data) and/or swap them with another disk and see if problem follows or stays with same disk.

Sorry, I should have included more information in my initial post. All four of my drives are in a DAS that connects to a mini-PC over USB. I rearranged the drives in the bays to test whether the bay holding the parity drive had failed, but all three of my data drives mount correctly regardless of which bay they are in.

Edited Saturday at 07:38 PM3 days by Hunter M

It disconnected. Will probably keep happening randomly, that's why USB devices are not recommended for array/pool use.

Aug 29 12:36:17 Evergreen kernel: usb 4-1.3: USB disconnect, device number 5

Edited Saturday at 09:18 PM2 days by Kilrah

2 hours ago, Kilrah said:

It disconnected. Will probably keep happening randomly, that's why USB devices are not recommended for array/pool use.

Aug 29 12:36:17 Evergreen kernel: usb 4-1.3: USB disconnect, device number 5

I wasn't aware that USB connections weren't recommended. I don't fully understand all of this stuff, but if usb disconnected, wouldn't all 4 drives not be available? As opposed to just the individual Parity Drive? The DAS is connected my mini-pc with single USB-c cable.

Edited Saturday at 11:51 PM2 days by Hunter M

Depends how it's built, he DAS could simply internally be one USB hub with each drive having its own USB interface connected to it, so each drive could disconnect from the hub individually.

Edited Sunday at 09:21 AM2 days by Kilrah

This is the DAS, if that is helpful. I am trying to understand why this specific drive is marked as unrecognized, but all of my other drives work regardless of the bay they are connected to. Could it be something with the specific drive? The SMART tests all passed without errors and it has relatively low POH.

TerraMaster Official Store

D4-320

High-Speed Data Transmission: Utilizing the USB 3.2 Gen2 protocol, the D4-320 hard drive enclosure achieves data transfers up to 10Gbps. With four hard drives installed, it delivers read/write speeds

Edited Sunday at 02:05 PM2 days by Hunter M

3 hours ago, Hunter M said:

Could it be something with the specific drive? The SMART tests all passed without errors and it has relatively low POH.

Possible the PCB has some issue with the SATA connection, and when that drops the USB adapter also drops yes...