Q:

ZFS System on Production

Do you know/have any system which works on ZFS such as RDMS? If yes, what is your setup? FreeBSD, ZFS on Linux etc.

A:

Yes, ZFS can support production workloads, such as hosting virtualization systems, running an Oracle database or general NAS or block-level storage presentation.
What are you interested in doing?
Edit:
This depends on your implementation, but ZFS on Solaris, NexentaStor, OpenIndiana, FreeBSD and even on Linux, have been extremely stable and solid for me so far. 
Some other user experiences here: ZFS Data Loss Scenarios

