Bug 18460

Summary: Allow installation on a btrfs subvolume
Product: Mageia Reporter: Alejandro Vargas <alejandro.anv>
Component: InstallerAssignee: Mageia tools maintainers <mageiatools>
Status: NEW --- QA Contact:
Severity: enhancement    
Priority: Normal CC: 79625490833, bequimao.de, marja11, thierry.vignaud, tmb, zen25000
Version: Cauldron   
Target Milestone: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Source RPM: CVE:
Status comment:

Description Alejandro Vargas 2016-05-15 13:27:57 CEST
One of the more usefull features of the btrfs are the subvolume snapshots. If you use a subvolume instead of the main filesystem, you can create snapshots and revert changes whenever you want.

Suse and Ubuntu can install the system on a subvolume maned "@" and mount this as root. If you want to make changes without risk, you can rename @ as simething else and  create a new @. Then you can switch between them and hace a backup of the system.
Barry Jackson 2016-05-15 18:43:14 CEST

CC: (none) => zen25000

Ulrich Beckmann 2016-05-16 18:22:21 CEST

CC: (none) => bequimao.de

Comment 1 Ulrich Beckmann 2016-05-16 18:28:07 CEST
Did you define the intented subvolume as default subvolume? What is the error message? I did not test it so far. I am waiting for another batch of isos.

Greetings
Ulrich Beckmann
Comment 2 Marja Van Waes 2016-05-19 09:55:20 CEST
Shouldn't this already be possible, as long as you don't put /boot on a subvolume?

CC: (none) => marja11, thierry.vignaud, tmb

Comment 3 Ulrich Beckmann 2016-05-24 10:16:50 CEST
Hi Marja,

It should be possible to prepare a partition with predefined subvolumes. But you can neither mount these subvolumes to the correct mountpoints during or before installation, nor they would be added to /etc/fstab.

One subvolume "@" is already an improvement, as you never can delete the root subvolume (subvolid = 5), when the default subvolume passes to another snapshot. OpenSUSE's set of subvolumes however is far more detailed. I had converted an installation of Mageia Cauldron to such a set of subvolumes. 

Greetings,
Ulrich
Thierry Vignaud 2016-06-23 08:02:58 CEST

Blocks: (none) => 416

Comment 4 Ulrich Beckmann 2016-06-23 12:00:32 CEST
I tested an installation into a btrfs partition with predefined default subvolume @@@ with Mageia-6-sta1-LiveDVD-PLASMA5-x86_64-DVD.iso of Jun 19.
You'll have to select "Use existing partitions" and unmark formatting. It works even with an btrfs raid configuration. 

It failed when installing the bootloader. But I still have to verify, if it depends on the configuration, and then file another bug.

Best regards,
Ulrich
Comment 5 Ulrich Beckmann 2016-06-23 13:42:10 CEST
Testcase to Comment #4 (ext4, not btrfs)
https://bugs.mageia.org/show_bug.cgi?id=18774

Ulrich Beckmann
Comment 6 Ulrich Beckmann 2016-06-23 17:54:19 CEST
I repeated the test with the classical iso
UUID="2016-06-20-21-52-36-00" LABEL="Mageia-6-sta1-x86_64" TYPE="iso9660" PTUUID="7c894d90" PTTYPE="dos" PARTUUID="7c894d90-01"

After unchecking "Format" I saw a rapid message "Formatting ... But obviously it did not format anything. The prepared btrfs partition remained intact, and I got a sucessful installation including grub2-bootloader (UEFI).

So it is possible to install Mageia 6 to btrfs with predifined subvolumes.
--------------------------------------------------------------------------
[root@localhost ~]# btrfs filesystem  show /dev/sda12
Label: 'Mageia-Test'  uuid: 191c07a2-4099-4276-9fdf-dc6454db70f0
        Total devices 2 FS bytes used 3.82GiB
        devid    1 size 11.72GiB used 3.02GiB path /dev/sda12
        devid    2 size 11.72GiB used 3.00GiB path /dev/sda14

[root@localhost ~]# mount /dev/sda12 /mnt
[root@localhost ~]#
[root@localhost ~]# btrfs subvolume list /mnt
ID 257 gen 10139 top level 5 path @@@
ID 259 gen 10105 top level 257 path var/lib/machines
[root@localhost ~]#
[root@localhost ~]# btrfs subvolume get-default /mnt
ID 257 gen 10139 top level 5 path @@@
----------------------------------------------------------------------------

Best regards,
Ulrich
Comment 7 Ulrich Beckmann 2016-07-09 09:58:58 CEST
Dependency to https://bugs.mageia.org/show_bug.cgi?id=18460 removed.

Blocks: 416 => (none)

Samuel Verschelde 2016-09-09 08:59:41 CEST

Assignee: bugsquad => mageiatools

Comment 8 sturmvogel 2023-04-22 20:58:34 CEST
*** Bug 31832 has been marked as a duplicate of this bug. ***

CC: (none) => 79625490833

Comment 9 Nikolay Sabelnikov 2023-04-22 21:06:06 CEST
the error has been around for many years, but it has not been fixed yet.