View the refurbished HP 2GB P-series Smart Array Flash Backed Write Cache 631681-B21 633543-001 quickspecs here
This refurbished Flash Backed Write Cache (FBWC) uses NAND 6 flash devices to retain cache data and super-capacitors (super-caps) instead of batteries to provide power during a power loss. The refurbished FBWC offers significant advantages over the HP Battery-Backed Write-Cache (BBWC) system. Since the FBWC writes the contents of memory to flash devices, there is no longer a 48-hour battery life limitation and the data will be posted to the disk drive on the next power up.
Specifications