Managing USB device names

[Giorgos Keramidas]

On 2007-05-25 09:09, Chris Kottaridis <chriskot at quietwind.net> wrote:
> I am using USB to connect an external disk drive. It seems to get
> assigned a different device name when it connects in. The names seem to
> cycle through /dev/da* where * is changing on each disconnect and
> reconnect.
>
> With this going on I can't add a /etc/fstab entry.
>
> Is there a tool/package that can manage things so that when I plug in
> the device it will get mounted to a specific directory without manual
> intervention ?

GEOM_LABEL can help a lot here.

I have a USB stick which contains a UFS file system created with:

    # newfs -L GKER /dev/da0s1a

Now if geom_label.ko is loaded and this USB disk is attached, the
GEOM_LABEL support creates a special /dev node at `/dev/ufs/GKER':

: kobe kernel: umass0: <JetFlash Mass Storage Device, class 0/0, rev 2.00/1.41, addr 2> on uhub4
: kobe kernel: umass0: Get Max Lun not supported (STALLED)
: kobe root: Unknown USB device: vendor 0x058f product 0x6387 bus uhub4
: kobe kernel: da0 at umass-sim0 bus 0 target 0 lun 0
: kobe kernel: da0: <JetFlash TS1GJF150 8.07> Removable Direct Access SCSI-2 device
: kobe kernel: da0: 40.000MB/s transfers
: kobe kernel: da0: 979MB (2007038 512 byte sectors: 64H 32S/T 979C)
: kobe kernel: GEOM_LABEL: Label for provider da0s1a is ufs/GKER.

# ls -ld /dev/ufs/GKER
crw-r-----  1 root  operator  -   0, 176 May 26 04:31 /dev/ufs/GKER
#

The device node at `/dev/ufs/GKER' is directly mountable:

# mount -o ro /dev/ufs/GKER /mnt/flash
# mount | fgrep /mnt/flash
/dev/ufs/GKER on /mnt/flash (ufs, local, read-only)
#

Using GEOM_LABEL support and the geom_label.ko kernel module, you can
assign names to your filesystems which persist across mount operations,
so it will be easier to mount them at predictable places.

Regards,
Giorgos