The write cache on Unity also is battery backed.  The difference between VNX vaulting and Unity vaulting is the location where the data is vaulted to (system drives on VNX, internal M2 SSD on Unity).  Both still need the battery to do the vaulting process in the event of a catastrophic power failure.
Hi, anyone has experience in disabling Battery (BBU) alerts on Unity ?   Any help, Much appricaited.   Many Thanks, Vivek       
Disabling alerts- Battery