The HP Smart Array P420 Controller is a low profile, 6 Gb/s, PCIe 3.0, Serial Attached SCSI (SAS) RAID controller that provides enterprise class, storage performance & data protection for select HP Pro Liant Gen 8 rack & 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 among all models of Smart Array controllers allows simple & easy migration at any time when needs for higher performance, capacity, & availability increase. Even new generations of Smart Array controllers can understand the data format of previous generations of Smart Array controllers.