Seamless: Transparent Storage Access Through Smart Switches

This paper presents Seamless, a switch-based accelerator for disaggregated SSD-based systems. Seamless comprises two fundamental components: (1) a hardware-accelerated, unified remote storage protocol that ensures efficient data access to Flash and remote memory. (2) A hardware-accelerated concurrency protocol with a simple interface like a buffer manager: fix(page_id, {exclusive, shared}) for acquiring page latches and unfix(page_id) for releasing them. Seamless achieves this by using a P4-programmable switch. To enable transparent storage access and caching, we maintain each page's location within the switch, whether in memory or on an SSD. Upon receiving a page request, Seamless determines the page's location and rewrites the communication protocol at line rate to NVMe-oF or RDMA accordingly. We manage the latches directly on the switch to maintain consistency and provide concurrency control. We show initial promising results for switch-based acceleration: Seamless hard-level accelerated protocol outperforms a software-based RDMA-optimized system by 20%.