Howtoforge posted a guide about setting up btrfs Filesystem with RAID1 on a Hetzner Server

This tutorial shows how to install Ubuntu 12.10 on the btrfs filesystem (with RAID1) on a Hetzner server with two hard drives. While Hetzner's installimage tool doesn't list btrfs as a supported filesystem and only supports software RAID with /dev/md devices, it is still possible to achieve this setup and use the built-in RAID support in btrfs instead of using /dev/md devices.

  Using The btrfs Filesystem (With RAID1) With Ubuntu 12.10 On A Hetzner Server