Flash Disk

Giorgos Keramidas keramida at ceid.upatras.gr
Fri Jan 6 04:14:17 PST 2006


Hi,

Please don't remote the list from the recipients of the message, unless
the reply contains confidential material that you don't wish to disclose
to all the subscribers of the list.  By keeping the list, you ensure
that other subscribers may reply too in case I'm wrong about something,
and you make it possible for future readers who find the thread in the
archives to read all the relevant material.

On 2006-01-06 00:07, Teilhard Knight <teilhk at crosswinds.net> wrote:
>> When I plug my USB JetFlash disk, the following appears in
>> /var/log/messages (and the system console, but I mostly use X11
>> these days):
>>
>>    umass0: USB Flash Disk, rev 2.00/2.00, addr 2
>>    da0 at umass-sim0 bus 0 target 0 lun 0
>>    da0:  Removable Direct Access SCSI-2 device
>>    da0: 1.000MB/s transfers
>>    da0: 250MB (512000 512 byte sectors: 64H 32S/T 250C)
>
> I get something similar too. The Device Node is created all right.

Cool!

>> When you plug the USB flash disk in, /dev/da0 (or another daX
>> device) is automatically created.  If the flash disk already has
>> partitions (they usually come with a single FAT partition),
>> you'll also see da0s1 or something similar:
>>
>>    # ls -l /dev/da*
>>    crw-r-----  1 root  operator  -   4,  44 Oct 16 17:38 /dev/da0
>
> Yes, I also get something similar to this.

That's nice.  It means that the kernel has recognized the flash disk as
a "block device" and the CAM layer of the kernel has created a 'direct
access' disk device for it -- much like it does for SCSI disks.

>> If you see only da0, it's possible that the 'raw disk' is
>> formatted using FAT, without a real BIOS-style partition, which
>> means that you should be able to 'mount' it with something like:
>>
>>    # /sbin/mount_msdosfs /dev/da0 /mnt
>
> I do not only see da0 above and this command results in: "mount_msdosfs:
> /dev/da0: Invalid argument"

The flash disk is not formatted, so you'll have to create a filesystem
on it.  I did this for mine, using fdisk(8) and bsdlabel(8), as
described in the following post of my old weblog:

    http://keramida.serverhive.com/weblog/archives/2004-10-16/using-a-usb-20-flash-mini-disk-on-freebsd

Enabling USB 2.X will also increase the access speed of the flash disk a
lot, so you may want to read this too:

    http://keramida.serverhive.com/weblog/archives/2005-06-23/usb-2x-support-in-freebsd

> You told me how to mount my flash disk in case the command "ls -l
> /dev/da0" results incomplete or I have the disk raw formatted. But
> what should I do if I get all similar to what you get? In other words,
> how do you mount your flash disk?

If you successfully mount the disk once, using the mount(8) and the
related utilities (mount_msdosfs, etc), then you can add a line in your
``/etc/fstab'' file to make things easier the next time.  My USB disk
doesn't have slices these days (just a UFS filesystem on it) so the
relevant line from fstab is:

    /dev/da1a /mnt/jflash ufs rw,noauto,noexec,nosuid 0 0

Regards,
Giorgos



More information about the freebsd-questions mailing list