Geom, MBR, labels, and usb sticks

[Warren Block]

On Thu, 19 Jul 2012, Dave Hayes wrote:

> # gpart show da0s2
> =>       0  15567804  da0s2  BSD  (7.4G)
>          0        16      2  freebsd-ufs  (8.0k)
>         16  15567788      1  freebsd-ufs  (7.4G)
>
> Now I want to label the partition da0s2a. From the documentation in the man 
> pages, I seem to be being told that
>
> # gpart modify -l foo -i 1 da0s2a
>
> will not work, and it doesn't:
>
> gpart: Invalid argument

No, gpart's labels are for GPT partitions.

> So let's try newfs:
>
> # newfs -L foo /dev/da0s2a
> ...
> # gpart show -l da0s2
> =>       0  15567804  da0s2  BSD  (7.4G)
>          0        16      2  (null)  (8.0k)
>         16  15567788      1  (null)  (7.4G)
>
> and still the labels do not show up.

They won't show in gpart because they are filesystem labels.  They will 
show in 'tunefs -p' or 'file -s'.

> I really do want to be able to mount 
> /dev/ufs/foo as the root device, but as I understand things if gpart doesn't 
> show the label then the glabel subsystem won't set up the proper device file.
>
> What gives here? Am I missing something important?

There is more than one type of label.  glabel(8) has a list that 
includes the device directory where the label appears.