In relation to the outdated post http://www.solaris-cookbook.eu/linux/debian-kanotix-proxmox-install-zfs-native/

Things have become much easier now

How to install ZFS native on Debian 7 or Proxmox 3.x

1) become root

sudo su –

2) Install ZFS

wget http://archive.zfsonlinux.org/debian/pool/main/z/zfsonlinux/zfsonlinux_3%7Ewheezy_all.deb
dpkg -i zfsonlinux_3~wheezy_all.deb
apt-get update
apt-get install debian-zfs

kernel upgrade

After updating the Kernel you most likely have to do the following steps:

make sure you have the headers installed (proxmox example)

aptitude install pve-headers-$(uname -r)

(it will pick the current running kernel version. If you just updated the kernel you better reboot first.)

ln -s /lib/modules/$(uname -r)/build /lib/modules/$(uname -r)/source

aptitude reinstall spl-dkms  zfs-dkms