For those interested in the clonedb feature of Oracle Direct NFS, check out MOS: Clone your dNFS Production Database for Testing [ID 1210656.1]
On the ZFSSA, we have the ability to create snapshots and offer clones of our snapshots. From a ZFSSA perspective, it is extremely simple to create snapshots and clones of snapshots via the BUI or CLI. For customers with Exadata and ZFSSA, we obviously have options. We can experiment with clonedb or leverage the storage appliance technology.
As a DBA, you may want to have the control yourself, especially, if you do not have control over the filer. Check out this post by Kevin Closson. He does a great job introducing the concept and showing you how to do it. If you read to the end of his post, he provides links to couple of great videos on youtube.