Optically connected memory for disaggregated data centers.

• Optical memory disaggregation for data centers achieves low energy-per-bit consumption. • Main memory disaggregation using state-of-the-art optical devices. • First evaluation of both energy-per-bit and system-level performance for main memory disaggregation with optical devices. Recent advances in integrated photonics enable the implementation of reconfigurable, high-bandwidth, and low energy-per-bit interconnects in next-generation data centers. We propose and evaluate an Optically Connected Memory (OCM) architecture that disaggregates the main memory from the computation nodes in data centers. OCM is based on micro-ring resonators (MRRs), and it does not require any modification to the DRAM memory modules. We calculate energy consumption from real photonic devices and integrate them into a system simulator to evaluate performance. Our results show that (1) OCM is capable of interconnecting four DDR4 memory channels to a computing node using two fibers with 1.02 pJ energy-per-bit consumption and (2) OCM performs up to 5.5× faster than a disaggregated memory with 40G PCIe NIC connectors to computing nodes. [ABSTRACT FROM AUTHOR]