Boot with root on a BTRFS RAID1 disk setup

Describe your issue

What the title says. I wish to boot using the postmarketOS initramfs, with the root on a BTRFS RAID1 disk setup.

It seems the only reason this does not currently work, is because BTRFS devices are not scanned for before attempting to mount them.

What's the expected behaviour?

The device performs btrfs device scan, and boots normally.

What's the current behaviour?

The device fails to mount the root partition.

How to reproduce your issue?

• Normal BTRFS filesystem install.
• btrfs device add [sdcard] /
• btrfs balance start -dconvert=raid1 -mconvert=raid1 /
• Reboot.

What device are you using?

pine64-pinephonepro

On what postmarketOS version did you encounter the issue?

• edge (master branch)

• v24.12

• v24.06 (supported until 2025-01-23)

• I confirm that the issue still is present after running sudo apk upgrade -a

On what environment did you encounter the issue?

Environments

• COSMIC
• GNOME Shell on Mobile
• Phosh
• Plasma Mobile
• Sxmo (Wayland/Sway) Please post the output of sxmo_version.sh
• Other: Please fill out

Which init system are you using?

• OpenRC
• systemd

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in yyyy-mm-dd format)

2025-03-21

Additional information

postmarketOS is a wonderful project, and I am grateful of all those who contribute.

I'm wondering if some kind of a workaround would be possible using the initramfs hooks? The wiki pages are a bit vague with how exactly they work, and experimenting with them myself is not something I can spare the energy for right now.

But if someone has any potential solutions, I am able to do tests.

added device-pine64-pinephonepro discussion initramfs type::feature labels

Hey @fluvf, you're not the first to have this want. There was an open MR implementing this which got lost during the gitlab migration, I have re-opened it and rebased it so you can give it a try. You can do git -C $(pmbootstrap config aports) checkout btrfs-multi-device and then build a fresh image (pmbootstrap -y zap)

!5508 (merged)

Please let us know if it works and we'll get that merged!

mentioned in merge request !5508 (merged)

Went the mrtest route, everything works as it should. Thank you!

I hope this can be backported to the latest stable as well, as I have some devices which would benefit from that, but I completely understand if that's not appropriate.

closed with merge request !5508 (merged)