USB *-IN-1 card readers

[Alan Dayley]

These multi-card readers can cause problems for some users.  They present
each slot as a separate logical unit (LU) on a single device.  If the
kernel you are using is not configured for multiple LUs on a device, you
will only see one slot.  Many distros provide a kernel binary with
multi-LU support disabled since most SCSI devices only ever are used with
one LU.

This page gives some detail: http://www.cs.sfu.ca/~ggbaker/personal/cf-linux

Background Points:
- USB storage devices, including card readers, are mapped to the OS as
SCSI devices.
- SCSI devices can have multiple logical units.
-- An LU is a subset of the device as a whole.  For example, a SCSI hard
disk drive can be divided into two logical units so that the host "sees"
two hard drives contained within the one physical device.
- *-in-1 readers present each slot as a separate LU.

Perhaps this advice can get you around the issue if you don't want to
rebuild your kernel:
http://www.redhat.com/archives/rhl-beta-list/2004-May/msg00238.html
Or try this one: http://lists.debian.org/debian-knoppix/2003/07/msg00026.html

None of the above references address how to configure and build a kernel. 
If you need to do that, let us know.

Alan

On Wed, August 30, 2006 8:36 am, Nathan England wrote:
>
> That is what I expected to happen, but it showed only one drive and it
> would
> not let me mount it. I tried many ways of plugging it in with and without
> the
> card inserted. Without the card, the sda and sg devices didn't exist, but
> with the card in, sda1 and sg0 showed up, but I could do nothing with
> them.