 "HPE Smart Array P421/2GB with FBWC - storage controller (RAID) SATA 6Gb/s" " HPE 6Gb/s 631674-B21 RAID Controllers CDW.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." 
 "291966-B21 HP Smart Array 641 Controller", "Null" "New 291966-B21 Controller Wholesale Price 291966-B21"
"Description:Smart Array 641 Ultra320 Controller with 64MB Cache 64-bit 133MHz PCI-X PC Board - Has one Internal 68-pin connector - Can add 128MB Battery Backed Write Cache (BBWC) ModuleSee optional BBWC BelowPart Number(s)Option Part# 291966-B21
Spare Part# 305414-001" 
 Specifications: Category Proliant Controller Sub-Category SCSI PCI-X Generation 641 Part Number 291966-B21 Products ID 8591 Board/Module Type Daughterboard Channels 1 Controller Type SCSI Drive Array (RAID) Drive Array Support RAID 0 1 5 10 Included Components Manual Installed Cache Memory 64MB Interface PCI, Ultra SCSI PCI, Ultra SCSI Maximum Cache Memory 128MB Maximum Number of Devices Supported 6 Maximum Transfer Rate 320MB/s System Type Linux, PC