QNAP TS-421U 4-bay 1U iSCSI NAS, Hot-swappable (TS-421U) Manage and share files in one centralized storage Back up business data with encrypted remote replication, Real-time Remote Replication (RTRR), and cloud-based storage backup Utilize NAS, iSCSI/ IP-SAN storage combo solution for server virtualization Facilitate iSCSI and virtualization deployment Increase efficiency with the support of Windows AD/LDAP, Windows ACL, and more Synchronize files between computers, tablets, and mobile devices Marvell 2.0GHz CPU, 1GB RAM, USB3.0