[NBLUG/talk] USB Memory Keys

[Mark Street]

I was going to get one of these today, 256M.  I held back....

You have to take it down to a lower level.

LABEL, you can move SCSI or IDE disks around on the bus/ribbon without having 
to UPdate /etc/fstab.  You may notice in /etc/fstab lines that begin with a 
LABEL=BOOT instead of a device /dev/sda1.  Remember, there are limited writes 
on these devices, you might want to set your fstab to not keep track of 
access times on files.  This is done with the tune2fs command.

tune2fs man page
-L volume-label
              Set  the volume label of the filesystem.  Ext2 filesystem labels
              can be at most 16 characters long;  if  volume-label  is  longer
              than  16  characters, tune2fs will truncate it and print a warn-
              ing.  The volume label can be used  by  mount(8),  fsck(8),  and
              /etc/fstab(5)  (and  possibly  others)  by specifying LABEL=vol-
              ume_label instead of a block special device name like /dev/hda5.

man parted

parted will work for labelling a vfat partition, mklabel will link with the 
appropriate device.  I am sure you can do a search on the net for this.

Then you can use devlabel to have the system link to the device when it is 
plugged in.

keywords, parted, mklabel, devlabel, usb, scsi, linux

SYNOPSIS
       devlabel [action] [options]

DESCRIPTION
       devlabel is a script which manages symlinks to storage devices on  your
       system.   This is accomplished by utilizing the inherent unique identi-
       fiers (UUID) that each device *should* have in order to maintain a cor-
       rectly  pointing symlink in the event that the device name changes (eg.
       /dev/sdc1 becomes /dev/sdd1).  By adding  entries  using  devlabel  its
       users  can instead reference all devices by their symlink and no longer
       care what the true name of their device is.  Similary,  consistent  raw
       device  access  can  also  be  guaranteed through use of devlabel as it
       treats entries in the format of /dev/raw/raw# as a special form of sym-
       link  so  that each raw device can consistently be bound to the correct
       storage device.

       devlabel works with both IDE and SCSI storage and has  been  integrated
       into  the  hotplug  system  to  allow  USB, IEEE1394 (firewire) and PCI
       detection and consistency.

On Sunday 21 December 2003 22:50, Jeremy Turner wrote:
> Hi all,
>
> I got a Lexar USB JumpDrive 2.0 for Christmas (okay, so we celebrated a
> little early this year), and with 2.6.0 and 2.4.22 it works just fine
> with the usb-storage driver and SCSI emulation.  Very nice.
>
> Okay, so here's my issue.  I now have three USB devices which use SCSI
> emulation (my Nikon Coolpix 4300 digital camera, the JumpDrive, and a
> Compact Flash reader).  How do I deal with multiple devices using
> /dev/sdX and plugged in at different times?  For example:
>
> ----- /etc/fstab ----- (relevant portion)
> /dev/sda1 /mnt/cf        vfat uid=jeremy,gid=jeremy,user 0 2
> /dev/sdb1 /mnt/jumpdrive vfat uid=jeremy,gid=jeremy,user 0 2
> ----- end /etc/fstab -----
>
> If I unplug the CF reader and the JumpDrive, and replugin the JumpDrive
> only, it gets registered as /dev/sda1.  The /etc/fstab manpage mentions
> labling an entry by LABEL='' or UUID='', but I can't seem to find a
> LABEL or UUID entry mentioned in the syslog.
>
> What I'd like to do is write a hotplug script to auto-mount the drive
> for me, but it doesn't seem like hotplug passes the right environment
> variables for me to figure out which sdX the device got!
>
> Anyone else ran into this problem before?

-- 
Mark Street, D.C.
Red Hat Certified Engineer
Cert# 807302251406074
--
Key fingerprint = 3949 39E4 6317 7C3C 023E  2B1F 6FB3 06E7 D109 56C0
GPG key http://www.streetchiro.com/pubkey.asc