A medium-sized company with 500 employees has a rapidly growing storage infrastructure with clustered mail， database， and file and print core business applications running on six servers. Using current direct attached SCSI storage pools to each server leads to inefficient utilization of storage space.They also have a backup device attached to each server. They want to consolidate their storage and backup infrastructure into a scalable， high availability and high performance solution. The customer’s top priorities are performance， cost， and availability. Which of the following backup solutions best satisfies the customer requirements？（）

A DS4000 SAN with flash copy enabled for volume mirroring
B. An iSCSI solution with dedicated backup server with SCSI attached tape library
C. A NAS solution with SCSI direct attached tape library with dedicated backup network
D. A DS4000 SAN with fibre channel attached tape library solution with dedicated backup zone