technical-information: Clarify the btrfs layout and their role

[omac777]

Ok so I understand /var holds the state for silverblue and is symlinked by:

    /home → /var/home
    /opt → /var/opt
    /srv → /var/srv
    /root → /var/roothome
    /usr/local → /var/usrlocal
    /mnt→ /var/mnt

But /sysroot/tmp is different:
/tmp → /sysroot/tmp

Then when I look at the x86_64 fedora silverblue directory layout, I see other directories not /var, are they all the immutable directories without state? Why was /var/home/ setup as different directory from /var/?

 $ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda      8:0    0 476.9G  0 disk 
├─sda1   8:1    0   600M  0 part /boot/efi
├─sda2   8:2    0     1G  0 part /boot
└─sda3   8:3    0 475.4G  0 part /var/home
                                 /var
                                 /sysroot/ostree/deploy/fedora/var
                                 /usr
                                 /etc
                                 /
                                 /sysroot

What were the specific commands used to create this btrfs layout of volume and subvolumes for the silverblue installer?

[travier]

It depends on the filesystem used. You should provide the output of findmnt to be able to explain that.

[travier]

The layout is made at install time in Anaconda, not sure where exactly.