Unlocking the Full Potential of Dual-Interface SSDs: A Comprehensive Hardware and Software Perspective

The legacy block interface for I/O benefits from data locality but faces challenges with I/O amplification due to the frequent small read-write operations common in most applications. Dual-Interface SSDs, which integrate block-interface Flash memory with byte-addressable memory, create opportunities for application redesign by reducing unnecessary read-write amplification on storage devices. However, current Dual-Interface SSD hardware remains limited in terms of size and functionality. Existing software designs for Dual-Interface SSDs often use the byte-addressable space as sequential logs with basic batch reclamation. While this space allows random access, and batch reclamation introduces significant tail latency caused by excessive read and write-back operations. To fully exploit the potential of Dual-Interface SSDs, we have developed a prototype on a hardware-software configurable platform. This publicly accessible Dual-Interface SSD offers realistic and optimized performance, overcoming the size and functionality limitations of previous designs. In addition, we demonstrate the ability of Dual-Interface SSDs to reduce write amplification in a traditional Copy-on-Write B-Tree data store. By employing two key techniques—Tree Pointer Relocation, which decouples indirection from the tree structure, and Tree Node Accommodation, which enables small-sized key-value pair updates to be processed directly in the byte-addressable space—we significantly improve the efficiency of storage operations. Our evaluation reveals that these techniques, when applied to Dual-Interface SSDs, achieve performance gains of 30.5% and 52.5% compared to a CoW B-Tree operating on traditional block-interface SSDs.