This posts describes how to create subvolumes in btrfs retrospectively (with existing data).
Encrypted btrfs RAID as root
This post describes how to setup a fully encrypted root btrfs on two disks, running in RAID 0.
Unlock Second LUKS Volume Automatically
This post shows some options for unlocking additional LUKS encrypted volumes automatically (on Antergos, but most of it should apply to other distros). It assumes that you already have your root filesystem on LUKS and want to add a encrypted none root volume.
I’m also using systemd-boot with a none encrypted boot/EFI partition.
Installing Ubuntu 16.10 on existing LUKS-encrypted LVM
This is a short overview of how to install Ubuntu 16.10 on an existing LUSK-encrypted partition containing logical volumes, and using two unencrypted partitions for /boot and /boot/efi/.