Edit since I figured out the source of the issue:

the real issue was with the usb port my enclosure was plugged into. it is technically a thunderbolt 3 port but I used it as a usb 10gb port.

I have been using a terramater D8 hybrid enclosure for 2 years with no issues connected to a normal usb port on my laptop. since it worked well, I got another one recently to expend. And since I ran out of ports on my laptop, I plugged it into the available

thunderbolt 3 port. and it worked well for smaller file transfers so I didn't even think there might be an issue there.

The issue became clear when I tried moving large files through that port and my system kept crushing completely.

the power went out, and after booting up again the pool said "unmountable: no filesystem".

I tried running filesystem check, but it just says in the GUI interface:

"ERROR: not a regular file or block device: /dev/

ERROR: cannot open file system

Opening filesystem to check..."

and when running the "btrfs check /dev/sdg" commend in terminal it says:

"Opening filesystem to check...

No valid Btrfs found on /dev/sdg

ERROR: cannot open file system"

and I'm not seeing any read/write activity on the drive (maybe a hundred reads a minute)

should I just roll the dice and use "--repair"?

tower-diagnostics-20260313-1807.zip

Edited March 31Mar 31 by Drn10n
added information

I assume you are using a USB enclosure since the device is /dev/sdX? No partitions are being detected; post the output from fdisk -l /dev/sdg

2 minutes ago, JorgeB said:

I assume you are using a USB enclosure since the device is /dev/sdX? No partitions are being detected; post the output from fdisk -l /dev/sdg

yes, it's a usb enclosure

Disk /dev/sdg: 7.28 TiB, 8001563222016 bytes, 15628053168 sectors

Disk model: SN850X 8000GB

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 33553920 bytes

Disklabel type: gpt

Disk identifier: C0CAA544-3141-427B-8E11-C64127C537BB

Device Start End Sectors Size Type

/dev/sdg1 2048 15628053134 15628051087 7.3T Linux filesystem

Hmm, the syslog shows no partitions on that device:

Mar 13 18:05:15 Tower emhttpd: /bin/lsblk -lnbo TYPE,PARTN,NAME,START,SIZE,PTTYPE,PARTTYPE /dev/sdg 2>&1

Mar 13 18:05:15 Tower emhttpd: disk sdg 8001563222016 gpt

Mar 13 18:05:15 Tower emhttpd: device sdg: no partitions

Mar 13 18:05:15 Tower emhttpd: import 31 pool device: (sdg) WD_BLACK_SN850X_8000GB_252164801372-0:0

Please reboot to clear the logs and post new diags after the array starts.

25 minutes ago, JorgeB said:

Hmm, the syslog shows no partitions on that device:

Mar 13 18:05:15 Tower emhttpd: /bin/lsblk -lnbo TYPE,PARTN,NAME,START,SIZE,PTTYPE,PARTTYPE /dev/sdg 2>&1

Mar 13 18:05:15 Tower emhttpd: disk sdg 8001563222016 gpt

Mar 13 18:05:15 Tower emhttpd: device sdg: no partitions

Mar 13 18:05:15 Tower emhttpd: import 31 pool device: (sdg) WD_BLACK_SN850X_8000GB_252164801372-0:0

Please reboot to clear the logs and post new diags after the array starts.

tower-diagnostics-20260313-2021.zip

Now it shows, this is very strange; it could be USB issues.

Mar 13 20:20:07 Tower emhttpd: /bin/lsblk -lnbo TYPE,PARTN,NAME,START,SIZE,PTTYPE,PARTTYPE /dev/sdg 2>&1

Mar 13 20:20:07 Tower emhttpd: disk sdg 8001563222016 gpt

Mar 13 20:20:07 Tower emhttpd: part 1 sdg1 2048 8001562156544 gpt 0fc63daf-8483-4772-8e79-3d69d8477de4

Mar 13 20:20:07 Tower emhttpd: device sdg partition: sdg1 type: gpt start: 2048 size: 7814025540, code: 0xfc63daf (5)

Mar 13 20:20:07 Tower emhttpd: import 31 pool device: (sdg) WD_BLACK_SN850X_8000GB_252164801372-0:0

Post the output from btrfs fi show

17 minutes ago, JorgeB said:

Now it shows, this is very strange; it could be USB issues.

Mar 13 20:20:07 Tower emhttpd: /bin/lsblk -lnbo TYPE,PARTN,NAME,START,SIZE,PTTYPE,PARTTYPE /dev/sdg 2>&1

Mar 13 20:20:07 Tower emhttpd: disk sdg 8001563222016 gpt

Mar 13 20:20:07 Tower emhttpd: part 1 sdg1 2048 8001562156544 gpt 0fc63daf-8483-4772-8e79-3d69d8477de4

Mar 13 20:20:07 Tower emhttpd: device sdg partition: sdg1 type: gpt start: 2048 size: 7814025540, code: 0xfc63daf (5)

Mar 13 20:20:07 Tower emhttpd: import 31 pool device: (sdg) WD_BLACK_SN850X_8000GB_252164801372-0:0

Post the output from btrfs fi show

Label: none uuid: 980c7b35-e594-4c01-824b-ba3323a50623

Total devices 1 FS bytes used 1.38TiB

devid 1 size 1.82TiB used 1.57TiB path /dev/sdh1

Label: none uuid: 4c1597c5-1b2b-4a66-9b49-911b3e5b4646

Total devices 1 FS bytes used 5.94TiB

devid 1 size 7.28TiB used 6.22TiB path /dev/sdg1

Label: none uuid: c2c6e219-be49-4c51-b0e3-8b63cab76fb6

Total devices 1 FS bytes used 12.86GiB

devid 1 size 25.00GiB used 20.00GiB path /dev/loop2

1 hour ago, JorgeB said:

Now it shows, this is very strange; it could be USB issues.

Mar 13 20:20:07 Tower emhttpd: /bin/lsblk -lnbo TYPE,PARTN,NAME,START,SIZE,PTTYPE,PARTTYPE /dev/sdg 2>&1

Mar 13 20:20:07 Tower emhttpd: disk sdg 8001563222016 gpt

Mar 13 20:20:07 Tower emhttpd: part 1 sdg1 2048 8001562156544 gpt 0fc63daf-8483-4772-8e79-3d69d8477de4

Mar 13 20:20:07 Tower emhttpd: device sdg partition: sdg1 type: gpt start: 2048 size: 7814025540, code: 0xfc63daf (5)

Mar 13 20:20:07 Tower emhttpd: import 31 pool device: (sdg) WD_BLACK_SN850X_8000GB_252164801372-0:0

Post the output from btrfs fi show

ummmmm, it started working again on its own. I suddenly noticed that my broken seeds are fixed out of nowhere. log doesn't say anything. no clue what changed.

I don't think it's the USB enclosure since it has been working solid for almost 2 years now.

thanks anyway. I will open a new thread if it reoccurs.