see links on left: http://zfsonlinux.org/
apt-get install python-software-properties add-apt-repository ppa:zfs-native/stable apt-get install zfsutils ubuntu-zfs
edit /etc/default/zfs (if you want to automount ZFS on boot; disabled by default)
Per default ZFS uses as much memory as available for its ARC cache. It should not be less than 512MB and a good value is 1/4 of available memory. This property can only be set during module loading, to restrict how much memory should be used to 512MB:
# echo "options zfs zfs_arc_max=512M" >> /etc/modprobe.d/zfs.conf