  Composable data centers (DCs) have been proposed to enable greater
efficiencies as the uptake of on-demand computing services grows. In this
article we give an overview of composable DCs by discussing their enabling
technologies, benefits, challenges, and research directions. We then describe a
network for composable DCs that leverages optical communication technologies
and components to implement a targeted design. Relative to the implementation
of a generic design that requires a (high capacity) dedicated transceiver on
each point-to-point link on a mesh optical fabric in a composable DC rack, the
targeted design can significantly reduce capital expenditure (by up to 34
times) because fewer transceivers are used. This is achieved with little or no
degradation of expected performance in composable DCs.
