Non-Volatile Memory or Nonvolatile Random Access Memory (NVRAM) is a form of static random access memory whose contents are saved when a computer is turned off or loses its external power source.
The advantage volatile storage device is that the daily routine reads/writes are made to the DRAM rather than to flash memory, which quite bluntly, eventually wears out.
And in applications that need to work 24/7 and require very high I/O rates, flash can become unreliable relatively soon.
