The article mentions copying databases using templates. Once your database has got big enough, that might not make sense. You could use a zfs fs for your clust

The article mentions copying databases using templates. Once your database has got big enough, that might not make sense. You could use a zfs fs for your cluster, snapshot it, then mount it in a new cluster. This would prevent copying the data, as zfs would do copy on write. So you get your isolation, and speed on large DB's. You do need to run a new postgres cluster though.