Bug#964818: Enable basic subvolume management for rootfs
Package: partman-btrfs
Version: 50
Severity: normal
Control: patch -1
Control: block 840248 by -1
https://salsa.debian.org/installer-team/partman-btrfs/-/merge_requests/1
I have tested the proposed changes and confirmed that they produce the
desired change.
Briefly, the problem: Installing Debian directly to subvolid 5 rather
than to a "rootfs" (like Fedora) or "@" (like SUSE and Ubuntu)
subvolume causes the following problems:
1. It makes it unreasonably difficult to move to a flat subvolume structure
2. It means that any snapshots of the rootfs creates a nested
subvolume rather than flat subvolume structure.
3. It blocks development of "Boot Environments" (consult the web for how these are used in Solaris and FreeBSD and how these would be useful in Debian).
4. It blocks the ability to stage a system upgrade in a @rootfs-sid or @rootfs-stable+1 subvolume and then pivot into this during a reboot; this is an example of how "boot environments" are useful.
There is precedent in Ubuntu for using a non-configurable method (they
additionally add a "@home" subvolume), and the Ubuntu installer does
not offer user configurability of subvolumes during installation.
My plan is thus:
1. After we have installation to subvolumes, add subvolume listing support to the rescue cd. This has the side-effect of being able to test "boot environments" from the rescue cd.
2. Activate boot environment support via grub-btrfs (#941627).
3. Long-term: add debian-installer support for user-configurable subvolume layout like Fedora and OpenSUSE have. Ideally I'd like to work on this as part of a btrfs-enablement team
Thanks,
Nicholas
CCing Cyril for Kibi ACK :-)
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