On Tuesday, 29 August 2017 22:27:36 BST Stroller wrote:
> > On 29 Aug 2017, at 19:15, Mick <michaelkintzios@gmail.com> wrote:
> > ...
> > This may have been mentioned already, but do you have sys-fs/udisks
> > installed?
> I did not.
> 
> > Check the output of udisksctl status/monitor/info and see what it reveals.
> > Then check if you can mount the device with udiskctl.
> 
> Having installed it I got "Error connecting to the udisks daemon: Could not
> connect: No such file or directory" a few times, until it occurred to me to
> start dbus. This may be the first time I've ever done so.
> 
> I was then able to get a status and info for the drive.
> 
> I cannot mount the drive using `sudo mount -v /dev/sdb1 /mnt/tmp`, but I am
> able to do so using `udisksctl`:
> 
>   $ sudo udisksctl mount -b /dev/sdb1
>   Mounted /dev/sdb1 at /run/media/root/6D18-12B4.
>   $

OK, this shows your kernel modules for mounting this device are not missing 
anything critical.


> Unexpectedly I find 10MB of files on the device - the same size as the
> loopback device which previously claimed to be mounted (and 6MB less than
> the files I had intended to copy to it).
> 
> No /dev/sdb1 has been created.
> 
> There are aspects of this I still don't understand, but I am grateful to
> everyone who has provided their time.
> 
> Stroller.

Many desktops use udisks to handle plugging/unplugging:

 https://wiki.gentoo.org/wiki/Udisks

which requires dbus and polkit.  However, if this is running headless and 
minimal without many of the desktop nice-to-have functionality, at least check 
you have added your user to the plugdev group and perhaps usb.

Instead of udisks you can also use:

- 'udevadm monitor' and plug your device to see what kernel and udev events it 
generates.

- 'lsblk -o +fstype,label,uuid,partuuid' to make sure the device mount point 
is not being claimed by some other mount like loopback - which I noticed in 
your output, but can't explain why it is happening ...  :-/

HTH.
-- 
Regards,
Mick