 "HPE Smart Array P421/2GB with FBWC - storage controller (RAID) SATA 6Gb/s" " HPE 6Gb/s 631674-B21 RAID Controllers CDWG.com
"The HPE Smart Array P421 Controller is a low profile, 6 Gb/s, PCIe 3.0, Serial Attached SCSI (SAS) RAID controller that provides enterprise class, storage performance, maximum external scalability, and data protection for select HP ProLiant Gen8 rack and tower servers. It features eight external 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 among all models of Smart Array controllers allows simple and easy migration at any time when needs for higher performance, capacity, and availability increase. Even new generations of Smart Array controllers can understand the data format of previous generations of Smart Array controllers." 
 "631671-B21 HP Smart Array P420/2GB Controller", "Null" "New 631671-B21 Controller Wholesale Price 631671-B21"
"Description:HP Smart Array P420/2GB FBWC 6Gb2-Ports Internal SAS ControllerPart Number(s)
Option Part# 631671-B21
Spare Part# 633538-001" 
 Specifications: Category Proliant Controller Sub-Category Smart Array Generation P420/2GB Part Number 631671-B21 Products ID 461057 Manufacturer HP Product Type Storage Controller Host Interface PCI Express 3.0 x8 Controller Interface Type Serial Attached SCSI (SAS), Serial ATA/6 Data Transfer Rate 600MB/s Buffer Size 2GB RAID Level 0 1 5 6 50 60 1+0 Drive Support 64 x Logical Memory 2GB ECC DDR3 SDRAM Form Factor Low-Profile Plug-in Card