The HPE Smart Array P421 Controller is an enterprise-class 6Gb/s controller that provides improved performance, greater external attach rate and lower maintenance. P421 controller is ideal for RAID 0/1, 1+0, 5, and 50. RAID 6 & 60 and additional advanced features are upgradeable with smart array advanced pack. P421 delivers increased server uptime by providing advanced storage functionality, including; online RAID level migration with FBWC, global online spare, and pre-failure warning.