My External Backup Drive Has Become Read-only / Unavailable

[suitej]

My Backup Station >> External Backup jobs have been running fine for at least two years.

Now, for reasons unknown, the drive is either read-only or unavailable. Here are a couple of snippets from the backup jobs' log:

[2019/09/04 20:15:01] Maximum retry times: 3; Retry interval in seconds: 60; Connection timeout in seconds: 120; Current retry number: 0.
[2019/09/04 20:15:01] Denying file type: Temp file.
[2019/09/04 20:17:08] # ERROR: Job is aborted because the external storage device is not available!
[2019/09/04 20:17:09] Job is aborted because the external storage device is not available!

[2019/09/05 16:55:57] Maximum retry times: 3; Retry interval in seconds: 60; Connection timeout in seconds: 120; Current retry number: 0.
[2019/09/05 16:55:57] Denying file type: Temp file.
[2019/09/05 16:56:21] Remove the "NAS2BKP/NAS2/docs/@Recently-Snapshot.backup" file.
[2019/09/05 16:56:21] Create the "NAS2BKP/NAS2/docs/@Recently-Snapshot.backup" symbolic link.
[2019/09/05 17:18:05] # ERROR: Can't create the "NAS2BKP/NAS2/docs/Vehicles/Cars" directory! (-30)
[2019/09/05 17:18:06] The synchronization stopped with errors.
[2019/09/05 17:18:06] Sync statistic: Total number of the folders: 111. Total number of the files: 965. Total updated size: 46 bytes. Average updating speed: 1024.00 (KB/sec). Time elapsed: 22 minutes 5 seconds
[2019/09/05 17:18:06] Job is aborted because one of the destination devices is readonly!

I've tried to copy a file using File Station and this gives an error too.

The drive is encrypted and has been unlocked.

I'd be grateful for any pointers to sort this one out! Thanks in advance...

[suitej]

A couple of other things I forgot to mention:

The drive is mounted in a USB caddy. A TECKNET UD037 Hard Drive Enclosure to be precise. It has two bays and they've both been working with the NAS until recently.

I am able to decrypt and mount the drive in a Ubuntu VM using the instructions found here: http://jonamiki.com/2015/05/17/mount-en ... -computer/ (remembering to use only the first 16 characters of my randomly generated 20 character password - thanks QNAP for that one!). I am able to read and write to the drive using Ubuntu Files (the GUI).

[Trexx]

I would suggest opening a helpdesk ticket with QNAP. They did make some changes related to external USB drives in QTS in the later 4.3.6 builds + around the time of the TR-00x chassis releases.

[suitej]

Thanks for the suggestion. I'll give it a go.

[suitej]

For the benefit of the community, here's the reply from QNAP support:

We only support the HDD's when they are in the QNAP NAS, we do not trouble shoot issues with individual drives in different operating systems in different encloses, this is beyond the scope of our support,

thank you