The Smart Array 642 Controller (SA-642) is a 64-bit, 133 MHz PCI-X dual SCSI channel PCI array controller for entry level hardware-based fault tolerance. Utilizing both SCSI channels (1 internal & 1 external) of the SA-642 means that you can configure up to 20 hard drives (6 internal, 14 external) to store up to 2.9TB of storage per PCI slot. The SA-642 provides high reliability & increased performance over the Smart Array 532, thus providing excellent value & lowering the total server ownership cost. In addition, the SA-642 is data compatible with all Ultra 320, Wide Ultra 3 & Wide Ultra 2 drives, offering an unparalleled degree of investment protection. Designed & integrated with HP entry-level & workgroup Pro Liant servers, this product provides worry-free data protection. The Smart Array 642 Controller provides Pro Liant DL & ML servers with an entry-level hardware RAID protection for OS & log files, where hardware RAID is needed at an entry-level price point.