The EXAR XRS10L120 is a Serial ATA port multiplier designed for next generation enterprise class disk array systems that use SATA mid-planes. The device is targeted at low cost storage applications. This function is used when one active host has to communicate with multiple SATA drives. The XRS10L120 supports up to 2 SATA drives and utilizes the full bandwidth of the host connection. The upstream ports of XRS10L120 can also be attached to a port selector (XRS10L210) or a Serial ATA Switch to provide redundancy in a more complex topology.