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 & data protection for select HP Pro Liant rack servers & tower servers. It features eight internal SAS ports & 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, & pre-failure warning. Data compatibility between HP Smart Array controllers means customers can easily upgrade to future Smart Array controllers.