I am going to suggest you do two things,
- Use
UUIDs instead of /dev/sd* in your fstab so that it is not messed up.
- Get you started with
udev so you can make your thumb drives appear as /dev/whatever
Section 1.
Ensure that all the devices listed in your fstab are plugged into the system. Wait a few seconds and then type
ls -l /dev/disk/by-uuid
This will give you something that looks like the following:total 0
lrwxrwxrwx 1 root root 10 Sep 24 20:19 4e36d61c-e6f4-4a1a-b760-45ee5a76e141 -> ../../sdc2
lrwxrwxrwx 1 root root 10 Sep 24 20:19 52a04f5d-2576-48d1-8340-544cc24e0fcd -> ../../sdc3
lrwxrwxrwx 1 root root 10 Sep 24 20:19 55a1d85d-e5f5-416e-adf7-3aed3e6309f1 -> ../../sdc1
lrwxrwxrwx 1 root root 10 Sep 24 20:19 5c8c3b19-5550-4411-8fc3-692aa94bb4af -> ../../dm-1
lrwxrwxrwx 1 root root 10 Sep 24 20:19 8bfea793-5cb2-480c-a4e3-2b3c331463bb -> ../../sdb3
lrwxrwxrwx 1 root root 10 Sep 24 20:19 a369bc5e-3bf0-454b-b04d-2936e343e959 -> ../../dm-0
lrwxrwxrwx 1 root root 10 Sep 24 20:19 e57e2838-2c56-43c3-b4b8-de0743c67181 -> ../../sdb2
lrwxrwxrwx 1 root root 10 Sep 24 20:19 f7772f0f-19d7-4ced-b0a0-b543e4bd54fe -> ../../dm-2
Now look up what you have in your fstab. Everywhere you have something like /dev/sdc1 I want you to replace it with something like UUID=55a1d85d-e5f5-416e-adf7-3aed3e6309f1. What this will do is tell mount to use the UUID to identify a device instead of it's location under /dev. These UUID are unique and last the lifetime of the filesystem.
Section 2.
udev is the service that is responsible for placing block devices (and other devices) under /dev in Ubuntu. You can actually write your own rules for udev that instruct it to make symlinks under /dev in a consistent way. The way udev works is that everytime a device is attached it scans a long list of rules and takes the actions specified by any that match. The matching is done by inspecting a bunch of parameters of the device such as, UUID, port it is plugged into, PCI address, etc. So you can identify your thumb drive by the filesystem's UUID and have a rule to map that to /dev/myThumbDrive and use /dev/myThumbDrive anywhere you would normally use /dev/sda1 (for example).
You can find a list of attributes to identify your drive with by typing
udevadm info -n /dev/sde --attribute-walk
looking at device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1/8-1:1.0/host6/target6:0:0/6:0:0:0/block/sde/sde1':
KERNEL=="sde1"
SUBSYSTEM=="block"
DRIVER==""
ATTR{partition}=="1"
ATTR{start}=="1"
ATTR{size}=="24242084"
ATTR{ro}=="0"
...
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1/8-1:1.0/host6/target6:0:0/6:0:0:0/block/sde':
KERNELS=="sde"
SUBSYSTEMS=="block"
DRIVERS==""
ATTRS{range}=="16"
ATTRS{ext_range}=="256"
ATTRS{removable}=="1"
ATTRS{ro}=="0"
ATTRS{size}=="31250432"
ATTRS{alignment_offset}=="0"
ATTRS{discard_alignment}=="0"
ATTRS{capability}=="51"
...
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1/8-1:1.0/host6/target6:0:0/6:0:0:0':
KERNELS=="6:0:0:0"
SUBSYSTEMS=="scsi"
DRIVERS=="sd"
ATTRS{device_blocked}=="0"
ATTRS{type}=="0"
ATTRS{scsi_level}=="3"
ATTRS{vendor}=="SanDisk "
ATTRS{model}=="Cruzer "
ATTRS{rev}=="1.00"
...
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1/8-1:1.0/host6/target6:0:0':
....
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1/8-1:1.0/host6':
....
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1/8-1:1.0':
...
SUBSYSTEMS=="usb"
DRIVERS=="usb-storage"
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8/8-1':
....
ATTRS{idVendor}=="0781"
ATTRS{idProduct}=="5530"
....
ATTRS{manufacturer}=="SanDisk"
ATTRS{product}=="Cruzer"
ATTRS{serial}=="20043513610A15E24E49"
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0/usb8':
....
looking at parent device '/devices/pci0000:00/0000:00:15.2/0000:05:00.0':
....
looking at parent device '/devices/pci0000:00/0000:00:15.2':
....
looking at parent device '/devices/pci0000:00':
....
And then you can create a rule that looks something like this:
KERNEL=="sd*", SUBSYSTEMS=="scsi", ATTRS{model}=="USB 2.0 Storage Device", SYMLINK+="myThumbDrive%n"
So that /dev/myThumbDrive1 can be used instead of /dev/sd[a-z]1
Alternate Method
This is too much typing of UUID's for my taste. Maybe it will be easier for you.
http://scnr.net/blog/index.php/archives/132
