If you want to change the SSH Message of the Day so that it doesn't show the default / drive space AND have it show the size of your zfs pool then you have to do the following to allow it to display. Please note that this is done on Ubuntu 14.04
First edit the disk.py file under /usr/lib/python2.7/dist-packages/landscape/lib with your favourite text editor and at the end of the STABLE_FILESYSTEMS entry add ', "zfs"' as shown in the screenshot below, then save and quit the editor
Next, edit the disk.py file under /usr/lib/python2.7/dist-packages/landscape/sysinfo with your favourite text editor and find the line main_info = get_filesystem_for_path("/", self._mounts_file, and edit the "/" path to the zfs file system you want, in my case its "/zfs/storage". Also edit root_main_info = get_filesystem_for_path("/"..... and replace the "/" with the same entry as above. These changes can be seen in the screenshot below. Save and then quit the editor. *Note a recent update removes the root_main_info line and is no longer required*
Done, the next time you ssh in to your server, you'll see your ZFS file system space!!!