[SOLVED] Arch next to Ubuntu on *same* BTRFS partition ?

ua4000 · 2016-02-05 19:19:55

Hi, at the moment I have a running Ubuntu, separete boot, swap and BTRFS for root+home:

Device        Start       End   Sectors   Size Type
/dev/sda1      2048  10487807  10485760     5G Linux filesystem
/dev/sda2  10487808  20973567  10485760     5G Linux filesystem
/dev/sda3  20973568 312580095 291606528 139.1G Linux filesystem

Theortically it should be possible, to create on the BTRFS partition (sda3) a subvolume, and then install ARCH into this?

So I could have Arch next to Ubuntu on the same partition?
Someone made this work in praxis too? Any tipps? Any tripping hazard?

Thanks very much!

(I know: I could also shrink the BTRS volume, create sda4 - this would be the "normal" way)

Last edited by ua4000 (2016-02-06 08:26:15)

Soukyuu · 2016-02-05 20:18:00

You could use a subvolume as root for your arch installation, using something like

linux   /arch/boot/vmlinuz-linux-ck root=UUID=23dfed6e-a649-4590-8062-4218fa910e12 rw rootflags=subvol=arch

as your boot options ("arch" being the name of your subvolume). Similarly, you could create another subvolume for your ubuntu installation and mv it there, just don't forget to change the boot options accordingly.

I'm using only arch on a partition, but several configurations+snapshots of it, and all of them are bootable without affecting each other. So I'd say it works quite well in practice for me.
The bonus of doing it the snapshot way is that you can save space by deduplicating some of the files, for example running duperemove. As always with "experimental" filesystems, don't forget to make a backup before attempting it.

Head_on_a_Stick · 2016-02-05 21:12:26

ua4000 wrote:

Theortically it should be possible, to create on the BTRFS partition (sda3) a subvolume, and then install ARCH into this?

Yes, I did this recently with a Debian jessie system.

I used https://wiki.archlinux.org/index.php/In … ting_Linux 'cos I couldn't be bothered messing around with an ISO image, it worked perfectly.

Using btrfs subvolumes is brilliant because both systems can use the entire drive space.

EDIT: For the mounting stage (fnar!) of the installation guide, use:

# mount -o subvol=arch /dev/sda3 /mnt

(this presumes the subvolume is called "arch")

Last edited by Head_on_a_Stick (2016-02-05 21:46:31)

ua4000 · 2016-02-06 08:25:48

Thanks for the answers!

Arch Linux

#1 2016-02-05 19:19:55