3PAR can do Synchronous Long Distance (SLD) which is a 3 site mode.
3PAR A ---> Synch ---> 3PAR B ---> ASynch ---> 3PAR C
A & B need to be within range/service time for Synch replication but C can be longer range and ASynch.
That's the only 3 system single volume mode I know, you can do lots of multi volume multi system setups but a volume can only exist twice or three times with SLD.
Could maybe fudge something with volume copies and a bunch of scripts for a periodic replication but might get messy.