I had four equivalent drives.
I had 2 x RAID 1 mirrors created with mdadm (ref)
I had both of these RAID 1 mirrors pooled together using mergerfs (ref)
I tried to run a burnin with bad blocks finder.
sudo bbf -c <MYDEVICECAPTCHACODE> burnin /dev/sda
I received an error.
ERROR - unable to open device: /dev/sda [Device or resource is busy]
Unmounting the drives
I went in and unmounted my mergerfs pool and both of my mdadm arrays from their respective spots in my /mnt folder.
$ sudo umount /mnt/storage $ sudo umount /mnt/mirror1 $ sudo umount /mnt/mirror2
I tried the burnin again here and was still receiving the ERROR.
Deactivating the mdadm array
I then stopped the mdadm arrays, zeroed their superblocks, commented out persistent references to the array in /etc/fstab file, commented out the array definition in my /etc/mdadm/mdadm.conf file, and updated initramfs so that the early boot process doesn’t try to find these arrays. (ref)
Happily ever after
Now my first 10TB drive is doing a burnin… only 28 more hours to go ?
Hopefully this helps someone!