Synology RS2421+ Rack 2U QC2,2GhzCPU/4Gb(up to 32)/RAID0,1,10,5,6/up to 12hot plug HDDs SATA(3,5' or 2,5')(up to 24 with RX1217RP)/2xUSB/4GigEth(+1Expslot)/iSCSI/2xIPcam(up to 40)/no rail repl RS2418+