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In this video you'll learn about labels and UUIDs. We already talked about it, so you

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already know why. It all has to do with device naming. Device names are generated by SystemD

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UDFD when the system is booting. And changes to hardware topology may result in changed

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device names. We have seen that. When I added a couple of NVMe devices and rebooted my system,

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suddenly the disk previously known as NVMe0n1 had become NVMe0n3. So if you have hard-coded

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device names in your ETCFS step, it will fail dramatically and you can start troubleshooting.

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That's not a good idea. And that is why you can use UUIDs and labels. UUIDs are automatically

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assigned while creating the file system. If at any time you don't see a UUID, well, the

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solution is simple. You haven't created the file system in that case. You can find BLKID

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to be pronounced as block ID to find currently existing UUIDs. Labels are human understandable

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labels that are written to the file system. And you need to create them yourself with

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the appropriate utilities. And the utility that you are going to use depends on the file

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system that you want to use. You use mkfs.whatever. It works for any file system with the uppercase

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L option to set a label while creating the file system. Or tune 2fs minus uppercase L

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to set the label on an existing EFC file system. And you can use XFS underscore admin minus

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uppercase L to set the label on an existing XFS file system. Now talking about XFS, you

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might get in a situation where you have duplicate UUIDs. This will happen if you clone a device.

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Because if you clone a device, you make an exact block by block copy of the contents

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of your device. And then the UUIDs are cloned as well. And the result might be duplicated

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UUIDs. And these prevent the file systems to be mounted properly. Now if you want to deal with

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that situation, you use the mount option no UUID. Or you just ignore the UUID and mount

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device name by device name or label. But that's a temporary situation. The nice situation is to

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use XFS admin minus uppercase U generate. That will generate new UUID on an XFS file system.

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Alternatively, there is UUID gen to generate a new UUID. And tune 2fs minus uppercase U to work

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with the new generated UUID, which next can be set on the device. So UUIDs normally are generated

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automatically, but you can generate them manually as well, which can be handy in some cases.