ML4W-OS Suggested BTRFS layout -- add more subvolumes #1447
Replies: 5 comments 22 replies
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I wrote a script to add the new subvols 
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Of course though it was for converting an existing ML4W config to the new layout live. But I had no data, etc yet. I would suggest no one else use it because the UUIDs are specific to my test system. If anyone runs it as-is your system will not boot up #!/bin/bash
set -e
UUID="b63b7e8a-c93b-4967-af61-b4855d554589"
MNT_TOP="/mnt/btrfs_root"
OPTIONS="rw,noatime,compress=zstd:3,ssd,discard=async,space_cache=v2"
echo "Creating mount point for top-level subvolume..."
mkdir -p "$MNT_TOP"
mount -t btrfs -o subvolid=5 UUID=$UUID "$MNT_TOP"
cd "$MNT_TOP"
echo "Creating new subvolumes..."
for sub in @root @srv @cache @tmp @log @snapshots @docker; do
if [ ! -d "$sub" ]; then
btrfs subvolume create "$sub"
else
echo "Subvolume $sub already exists, skipping..."
fi
done
echo "Migrating existing data..."
mkdir -p /mnt/current_root
mount -t btrfs -o subvol=/@ UUID=$UUID /mnt/current_root
# Use rsync if available for safer migration, otherwise cp -a
# Ensure the targets exist within the subvolumes
[ -d /mnt/current_root/root ] && cp -a /mnt/current_root/root/. @root/ || true
[ -d /mnt/current_root/srv ] && cp -a /mnt/current_root/srv/. @srv/ || true
[ -d /mnt/current_root/var/log ] && cp -a /mnt/current_root/var/log/. @log/ || true
umount /mnt/current_root
echo "Updating /etc/fstab..."
cp /etc/fstab /etc/fstab.bak
cat <<EOF >>/etc/fstab
# Newly added Btrfs subvolumes
UUID=$UUID /root btrfs $OPTIONS,subvol=/@root 0 0
UUID=$UUID /srv btrfs $OPTIONS,subvol=/@srv 0 0
UUID=$UUID /var/cache btrfs $OPTIONS,subvol=/@cache 0 0
UUID=$UUID /var/tmp btrfs $OPTIONS,subvol=/@tmp 0 0
UUID=$UUID /var/log btrfs $OPTIONS,subvol=/@log 0 0
UUID=$UUID /.snapshots btrfs $OPTIONS,subvol=/@snapshots 0 0
UUID=$UUID /var/lib/docker btrfs $OPTIONS,subvol=/@docker 0 0
EOF
echo "Cleaning up..."
cd /
umount "$MNT_TOP"
rmdir "$MNT_TOP"
echo "Done! Please verify /etc/fstab and reboot."After reboot I run: I forgot to add to script, but since I didn't test it with it. I left it out. |
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Ok. Great. That means, this is your custom setup. And you are running this script after the installation of ML4W OS? In that case and with this option in mind, I would keep the existing subvolumes from the default installation. |
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I think that it's better to do up front. There's always a risk of a problem or bug and end up with a non booting OS. Plus need to enhance the script to find the correct UUIDs. If you look at CachyOS, arch or Garuda BTRFS defaults they too break out subvolumes Cachy: Garuda: OpenSuse is slightly different |
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@dwilliam62 I have updated the installation script to install the archinstall btrfs subvolumes: 
Will be released with Live ISO 2.10.1 |
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Awesome! Thank you. I am sure other users will appreciate it also! |
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I will check. Should be possible. |
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Can you share a link to resources? |
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Not sure which you meant but the SDDM theme is here : https://github.com/JaKooLit/simple-sddm-2 SLIM is in the AUR repo, slim, and sliim-themes |
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I find that https://github.com/uiriansan/SilentSDDM is an interesting concept. Very customizable. |
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that is a very nice looking project. |
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Looks pretty good with catppuccin-mocha and the moutain image |
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Are there plans to have some GUI for managing snapshots if this will be included in base installation? Also are there plans for guide to migrate to btrfs if I have enough disk space to create copy of entire / on additional temporary drive or should i just backup and do fresh installation? |
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There are snapshot GUI tools for Linux already I don't know how you would migrate to BTRFS I think that would be way more work than backup data, install OS and restore data. But Archinstall and some other Arch distros can create a proper BTRFS layout (minus docker but that can be done after) |
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btrfs subv create @home_$USER_.ssh /mnt/home/$user/.ssh - rolling back ssh keys is not fun 😂😂😂 |
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Why is that needed over the already included @home ? |
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the reasoning is right there |
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An ssh key is a handshake that needs the same hand on both ends, you don't wanna cut off your hand and replace it with a different one 😭 |
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If you have a snapshot of @home that will also have $HOME/.ssh
…On Wed, Feb 11, 2026 at 1:09 AM ArekKubinski ***@***.***> wrote:
the reasoning is right there rolling back ssh keys is not fun 😂😂😂 and
I agree
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having additional snapshot for .ssh folder have no downsides and have upside of being able to leave keys while rollbacking changes to /home, please explain why you are against this and what downsides it introduce |
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I am not for or against it. Just trying to understand the use case better. Typically you restore files on "home" not roll back the entire subvolume. ML4W will have to document and explain it also. Many of his users are very new to Linux |
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My typical use case for snapshots is when I tinker with something and suddenly everything breaks and I don't know what broke so I do a rollback to working state, restoring files I usually do by using ctrl-z in editor while I still know what happened and whats changed. |
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That means you want to keep the status of .ssh and roll back the home folder separately if needed? |
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If you have dual side encryption (which you should if you're not gonna use a service like Tailscale) you need to never ever rollback the ssh subvolume. If you use a service like that you're fine but like he said it doesn't hurt |
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Hello,
I've been trying ML4W OS in a VM.
BTRFS is a great choice for filesystem. This is a layout that works well for me
Using more subvolumes better isolates functions and makes BTRFS snapshots more efficient. The docker one is very useful, i..e those using DistroBox for example.
Regards,
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