I have worked with LVMs for my job in the past, I am no expert but I think I can help.

Right, the issue you are seeing with your /boot is that the LVM partition is located right behind it, and the free space is located after the LVM partition.

This means that you can’t increase the size of /boot as the LVM partition is in the way.

This is if I understand it an issue stemming from when we used mechanical hard drives as standard, the parttion table still sees an SSD as a mechanical drive, where partition location is important.

So you simply can’t increase /boot without reinstalling the system.

As for your question why KDE’s partition manager sees your LVM partition as full, that is because it is almost full…

Let me explain.

LVM is an abstraction layer put on top of the disk/partition, here is the concept the LVMs use in your set up:

0. Disk
1. Partition
2. LVM Physical Volume
3. LVM Volume Group
4. Logic Volume
5. Filesystem

The partition manager kan only see layers 0, 1 and 2, it sees the disk, it sees the partition and it sees that the partition is an LVM PV.

The LVM PV takes up almost all the space in the partition, but it just hands that data up the LVM chain, to the LVM VG, that is where you can combine several PVs across several disks into one data set that you can use to create LVM LVs independantly.

So while the partition manager only see that there is an LVM PV in the partition, is has no idea about how that is used.

Now, there is a way to possibly move data and solve your issue, I have only done it on a test system.

You need another disk, and probably a liveUSB.

I will not give exact commands to run, but I will give enough information to make the concept clear, this is so you are required to read the official documentation before continuing.

To possibly solve this (or mess up your data completely, that is allways a risk when moving data around, make backups!) you need to do the following:

Get a new drive that can store all your data.

Make a single LVM partition

Make it an LVM PV and add it to the LVM VG that your current LVM is part of.

Move the LV from the old PV to the new PV (do not just expand the LV!)

Remove the old PV from the VG.

Delete the old LVM partition.

Increase /boot

Create a new LMV partition

Make it a new PV

Add this new PV to the old VG

Move the LV from the temporary PV on the new disk to the smaller PV on the old disk

Remove the temporary PV from the VG.

That should in theory resolve the issue.

Note however, this is a highly dangerous operation, the best thing to do would be to copy your data to new drive and reinstall the computer with the new partitions sizes set from the start.

Finally LVMs are damn cool, but they don’t offer redundancy by default, you can set up a software raid in LVM, but that is not something I have experience with