Overview: The Smart Array 4250ES Controller is a uniquely cable-free Extended SCSI (ES) controller design that enables hot-plug redundant array controllers inside an industry standard PCI servers. It works in the ProLiant 6000 7000 and 8000 servers and compatible with Wide Ultra2 and Wide-Ultra SCSI hard drives. In addition to having 64MB (56MB useable for read/write cache 8MB for transfer buffer and scripts memory) ECC-protected and battery-backed removable read/write cache this controller's three SCSI channels provide up to 120MB/s throughput. These three channels can support up to twenty-one 1 drives on a single controller for the Proliant 8000 (with 18.2GB drives you can add 382.2GB of storage) and can support twelve 1.6 drives or eighteen 1 drives in the Proliant 6000 and 7000. It supports Distributed Data Guarding (RAID 5) that allocates parity data across multiple drives and allows simultaneous write operations.