In a root shell run:
umount --force /srv/dev-disk-by-id-ata-WDC_WD20EFRX-68EUZN0_WD-WCC4M3ZD1HSR-part1
Then run:
ls -al /srv/dev-disk-by-id-ata-WDC_WD20EFRX-68EUZN0_WD-WCC4M3ZD1HSR-part1
Anything of interest in there?
Yes! but I ran it on /dev/disk/by-id/ata-KINGSTON_SA400S37120G_50026B76834417D9-part1 wich is the system disk that needs to be cleaned up
Result:
lrwxrwxrwx 1 root root 10 Aug 26 21:47 /dev/disk/by-id/ata-KINGSTON_SA400S37120G_50026B76834417D9-part1 -> ../../sdg1
WDC_WD20EFRX-68EUZN0_WD-WCC4M3ZD1HSR-part1
is the correct disk for the backups:
drwxrwxrwx 4 root root 4096 Feb 14 2019 .
drwxr-xr-x 11 root root 4096 Mar 11 21:09 ..
drwxr-xr-x 4 docker users 4096 Aug 25 08:55 backups
drwxr-xr-x 3 root root 4096 Feb 14 2019 nexus