I've started using Fedora Kinoite in a VM, and its default setup uses a Btrfs partition. I get that it uses Btrfs subvolumes to separate the OS image from mutable data like /etc and /home. However, I'm puzzled because when I check with the `mount` command, it indicates that the same subvolume (`/root`) is mounted at several different points like `/`, `/sysroot`, `/etc`, and `/usr`. I thought mounting a subvolume in different locations would show the same content, similar to a bind mount, but `/etc` and `/usr` don't have the same content. I'd love some clarification on how this works. I suspect the `mount` command might not clearly show the right subvolumes, as KDE Partitionmanager only shows one mount at `/sysroot`. Has anyone encountered similar issues or can provide insights?
3 Answers
You might want to check out the dedicated Btrfs community for deeper insights. They have a lot of discussions about unique behaviors and setups, which could really help clear things up for you!
It's really unusual to mount a Btrfs root with a regular mount like you described. The typical approach is to mount the subvolumes independently to ensure they act more like isolated partitions. By mounting them as individual subvolumes, you avoid any confusion. Plus, one of the perks of Btrfs is that it allows you to be flexible with storage without needing to allocate specific sizes for partitions! I suggest creating a test Btrfs on a USB flash drive and trying out some subvolumes—it’s a great hands-on way to learn!
Good idea! I’ve been trying to get a feel for Btrfs, and that sounds like a perfect way to experiment.
Btrfs subvolumes work differently from traditional filesystem mounts. When you see them as regular folders like `/etc` or `/usr`, it can be confusing. They’re technically not independent; it’s more about how they’re presented. When you mount using something like `mount -t btrfs -o subvol=etc /dev/device /etc`, it makes them appear isolated, but they share the same space. The key is realizing that a regular mount of Btrfs can make everything look like folders at the same level, which is why you might see the same subvolume appearing in different places with different contents. You might try checking `cat /proc/self/mountinfo` to get a clearer picture of what’s actually mounted where!
That makes sense! So, it’s like a visual representation issue? I'll check `mountinfo` next time for clarity.
Yeah, I’ll definitely explore that. I didn’t realize there was a dedicated space for Btrfs!