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In this video, you'll learn about labels and UUIDs.

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We already talked about it, so you already know why.

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It all has to do with device naming.

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Device names are generated by systemd UDFD when the system is booting.

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And changes to hardware topology may result in changed device names.

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We have seen that.

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When I added a couple of NVMe devices and rebooted my system, suddenly the disk previously

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known as NVMe0n1 had become NVMe0n3.

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So if you have hard-coded device names in your ETCFS step, it will fail dramatically

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and you can start troubleshooting.

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That's not a good idea.

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And that is why you can use UUIDs and labels.

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UUIDs are automatically assigned while creating the file system.

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If at any time you don't see a UUID, well, the solution is simple.

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You haven't created the file system in that case.

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You can find block ID, BLKID to be pronounced as block ID to find currently existing UUIDs.

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Labels are human understandable labels that are written to the file system.

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And you need to create them yourself with the appropriate utilities.

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The utility that you are going to use depends on the file system that you want to use.

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You use mkfs.whatever.

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It works for any file system with the uppercase L option to set a label while creating the

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file system.

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Or tune 2fs minus uppercase L to set a label on an existing exe file system.

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And you can use xfs underscore admin minus uppercase L to set a label on an existing

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XFS file system.

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Now talking about XFS, you might get in a situation where you have duplicate UUIDs.

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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.

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And then the UUIDs are cloned as well.

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And the result might be duplicated UUIDs.

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And these prevent the file systems to be mounted properly.

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Now if you want to deal with that situation, you use the mount option no UUID.

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Or you just ignore the UUID and mount the device name by device name or label.

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But that's a temporary situation.

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The nice situation is to use xfs admin minus uppercase U generate.

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That will generate a new UUID on an XFS file system.

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Alternatively, there is UUID gen to generate a new UUID.

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And tune 2fs minus uppercase U to work with the new generated UUID, which next can be

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set on the device.

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So UUIDs normally are generated automatically, but you can generate them manually as well,

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which can be handy in some cases.