LVM vs. BTRFS for new install

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Hi,

I am in the progress to try out manjaro and I want to install it on an old mac mini 2014 (intel i7). This machine happens to have a so called fusion drive, consisting of a 128G NVME SSD and (originally) a 1T spinning HDD. Some years ago I substituted the HDD by a 1T SSD. The result is the same, though faster disk speed.

Now there is fedora installed on the machine. Both disks are combined via lvm, or better said, on the NVME there is an EFI boot partition, an ext4 partition mounted as /boot and an lvm partition. On the SSD there is only a lvm partition. Both lvm partitions from both drives are combined to a logical volume, which contains the / root partition and a swap partition (8G) for fedora. Both drives have a GUID partition table, because that seems to be necessary as well as the EFI boot partition for that machine.

The fedora installer did helpfully assign this partition layout for me. I didn’t have to do anything special, except luks encryption for the logical volume and adapting the partitions inside it to add the swap. I had hoped that the manjaro installer would do something similar, but that is not the case. LVM is present as an option, but the buttons don’t work, let alone it recognises what the end user probably wants and assigns an appropriate layout…

The question is now, how can I achieve the result that the fedora installer did for me?
Doing everything manually from the live environment, using fdisk? I don’t feel very comfortable with this, it’s not my daily business and in the end I just want to have a working system, quickly. I am afraid that in the end nothing works anymore, especially with this kind of exotic hardware :smiley: . I don’t even know how to create an EFI boot partition with fdisk or a GPT.
Installing in the present partitions? This is offered by the manjaro installer, don’t know whether it works. Could be an alternative, but maybe I have some fedora artifacts laying around afterwards?
Deleting and recreating the current layout with the manjaro partitioning tool does not work. I tried that, but it told me that it could not create a GPT and installation failed.
Using btrfs subvolumes instead of lvm? As I read, it could be done by installing the system on the 128G NVME, assign EFI and /boot partitions first, and / with btrfs. Afterwards I could combine the SSD to it by expanding the btrfs of the /. That might be an option, but I never did that, too. Wherever I read, I see that there is RAID involved, and I don’t want RAID. I just want to have two partitions on two separate drives combined into one logical volume, just as lvm does.
Stick to fedora? Thats what I do right now, its not the worst option of all :smiley: . But I’d really like to try out manjaro…

Some advice would be nice, thanks

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If the priority is just glueing both drives together, then BTRFS is a better and easier choice, but you need to wipe everything then.

Just to illustrate this briefly:

  1. You install Manjaro with BTRFS on the SSD.
  2. then start Manjaro from the SSD.
  3. you add the empty HDD to the mounted path, something like this:
sudo btrfs device add /dev/sdXY /

So basically this means: Add /dev/sdXY, i.e. your block device, to the currently mounted system on /.

Then check:

sudo btrfs filesystem usage /

There should now be 2 block devices listed.

Congratulations, you have a JBOD with BTRFS. You can change the profile to RAID0/1 anytime, but at this point it will just fill up the space starting with the first block device.

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3

Use the manual partitioning method presented in Calamares (the Manjaro installer). No matter whether you use BTRFS or EXT4 (in an LVM configuration), the manual partitioning method is the easiest path toward achieving your goal.

It only takes some logical deduction, instead of “click, click, click”.

Regards.

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Two partitions on two separate drives combined into one logical volume → This is called JBOD / RAID0 see wikipedia RAID levels

So you get what you want.

Once there was a time where i never did this. Then i did it once. …
You may wish to read

About software Raid with btrfs

:footprints: