ok, so someone here asked me how i have made all these subvolume ****, here is a exact copy of the pm i replied to: [...] mkfs.btrfs -f /dev/mmcblk1 yeah right, WITHOUT any p1. direct from the block (the "-f" is not mandatory, it useful when you have problem because the device don't want to release it or something, whatever. try first without, if it works congrats, if you need it, use it) [...] btrfs subvolume create /mnt/microsd/Desktop btrfs subvolume create /mnt/microsd/Documents btrfs subvolume create /mnt/microsd/Downloads btrfs subvolume create /mnt/microsd/Music btrfs subvolume create /mnt/microsd/Public btrfs subvolume create /mnt/microsd/Templates btrfs subvolume create /mnt/microsd/Videos btrfs subvolume create /mnt/microsd/sdcard btrfs subvolume create /mnt/microsd/Pictures [...] cp -r -a -v /home/nemo/sdcard/ /mnt/microsd/sdcard cp /home/nemo/Pictures/Jolla/* /mnt/microsd/Pictures/Jolla/ cp /home/nemo/Video/Jolla/* /mnt/microsd/Videos/Jolla/ cp /home/nemo/Videos/Jolla/* /mnt/microsd/Videos/ (if you already have any music or something to those old directory: cp /home/nemo/Music/* etc ....) then, we can mount as you can see, the compress argument is here. btrfs is able to compress "on the fly", and, more, if the data is incompressible, it remain the same. afterward, btrfs as a flaw, it's "compress all the volume/subvolume or nothing" that why i mantioned it only time mount -o subvol=sdcard,compress /dev/mmcblk1 /home/nemo/sdcard/ [?] mount -o subvol=Videos /dev/mmcblk1 /home/nemo/Videos/ mount -o subvol=Desktop /dev/mmcblk1 /home/nemo/Desktop/ mount -o subvol=Documents /dev/mmcblk1 /home/nemo/Documents/ mount -o subvol=Downloads /dev/mmcblk1 /home/nemo/Downloads/ mount -o subvol=Music /dev/mmcblk1 /home/nemo/Music/ mount -o subvol=Pictures /dev/mmcblk1 /home/nemo/Pictures/ mount -o subvol=Pictures /dev/Public /home/nemo/Public/ mount -o subvol=Public /dev/mmcblk1 /home/nemo/Public/ mount -o subvol=Templates /dev/mmcblk1 /home/nemo/Templates/