The HP Smart Array P420 controller is a low profile, 6 Gbps, PCIe 3.0, Serial Attached SCSI (SAS) RAID controller that provides enterprise class, the storage performance and data protection for select HP ProLiant rack servers and tower servers. It features eight internal SAS ports and delivers increased server uptime by providing advanced storage functionality, including online RAID level migration (between any RAID levels) with flash back write cache, global online spare, and pre-failure warning. Data compatibility between HP Smart Array controllers means customers can easily upgrade to future Smart Array controllers.