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Identify disk device with the UUID

When linux system starts, auto mounting partition will be done by refering to the configuration file /etc/fstab (File System Table), in this file you specify the disk, the mount point and the type of mount to do at system startup:

# <file system> <mount point> <type>

<options> <dump> <pass>

/dev/sda1 /my/disk vfat default,umask=077,gid=46 0

0

In the above example /dev/sda1 is the device you want to be mounted in /my/disk

directory, but the name /dev/sda1 can change when you change the order on your controller or when you change the port where you connect your external usb-drive.
So the name of the device isn't an unique identifier of the specific disk; you need to refer

to it in a different way, using the UUID (Universally Unique IDentifier). The UUID is a specific identifier for this specific file system, it changes only when you reinitialize the filesystem but not when you change the order you connect it to you machine.

So you can change you /etc/fstab in this way and you no need to worry about the reordering of hard disk anymore:

UUID=1928b637-4daa-4073-b42c-14a05220ce8a /my/disk vfat defaults,umask=007,gid=46 0 0

To retrive the UUID of a specific partition you had different ways depending on your linux distribution, here are some example, try the one that fits your linux distribution:

dumpe2fs /dev/sda1 | grep -i uuid

blkid /dev/sda1

ls -l /dev/disk/by-uuid/