General :: Label Versus UUID In Fstab And Menu.lst?

I realized that my understanding of UUIDs in Linux to specifying hard disk partitions may be erroneous.

The proverbial wisdom is that one should not use hard-coded device specifications in fstab and in the boot menu.lst, such as /dev/sda1 etc. The reason normally given is that if hard disk order changes or the order of partitions change, then the entries will be incorrect since they are hardcoded to partitions following a specific order.

So my understanding was that using hard disk labels, in the form of LABEL=xxxx, or UUIDs in the form of UUID=some-uuid, would prevent these problems when disk order or partition order changed.

I decided to avoid the use of LABEL in case I wanted to change the LABEL on a partition to make the names of partitions more easily identifiable. I then thought that UUID was ideal since it never changed for a partition no matter even if I moved that partition to another drive or added another hard drive and thus changes the order of hard drives on my computer. I essentially thought that once UUID was determined for a partition, it never changed but was somehow part of the partition in the hardware of my computer.

Then I became curious of how a UUID was determined. I did this because I often make backups of partitions on external SATA drives and wanted to make sure that somehow the backup would not duplicate whatever Linux considers the UUID of a partition and present a Linux distribution with two UUIDS which are somehow the same and therefore confuse the Linux distribution to the point that I could not use it. I am aware that UUID means a unique id, but I wanted to make sure I understand how that unique id is determined in Linux. This is especially true since the tool I use to make backups of an entire partition is a Windows application, and not a Linux application, and I wanted to make sure that the backup partition UUID would not duplicate that of an existing partition.

In my very brief research in how a UUID is generated under Linux it appears that it is not something that is part of the hardware of the partition itself but rather a number generated by some parameters of the partition, one of which is the partition order.

If it is, it means to me that if I move a partition from one place to another, even on the same hard drive, or to another hard drive, a Linux distribution will no longer find the partition based on the UUID. In that case it seems as if the UUID is subject to the same weakness as the device specification in fstab and menu.lst in that the order of a partition or the placement of a partition on a particular hard drive will cause the designation to no longer refer to the same partition. In which case it appears to me that only the LABEL parameter is not subject to this weakness and as long as I keep distinct labels for all partitions on my hard drive I could theoretically move them around at will and a Linux distribution will find them correctly. I am aware of course that my computer must always find the boot partition to be able to boot a Linux distribution, so moving Linux parttions where I want them is subject to the ability of my computer to find them from the MBR of my hard drives. But in the main it now appears to me that the best way to insure that moving partitions does not keep a Linux distribution from botting correctly is to use LABEL, and not UUID, in fstab and menu.lst, and of course to make sure that if I decide to change the LABEL of a partition that I must change its entry in fstab and possibly menu.lst before rebooting that distribution.

If I have been wrong in my latest surmises I would appreciate being corrected, as the information I found on UUIDs and how they are generated may not be correct. Also if there is more exact information on exactly how partition UUIDs are generated in Linux I would appreciating anyone pointing it out to me.