Synology RS2821RP+ Rack 3U QC2,1GhzCPU/4Gb(upto 64)/RAID0,1,10,5,6/upto 16hot plug HDDs SATA(3,5' or 2,5')(upto 28 with RX1217)/2xUSB/4GE (1xExpslot)/iSCSI/2xIPcam(upto 40)/2xPS/no rail/3YW