MiTDM: Eliminating False Conflicts in Scalable MVCC in Disaggregated Memory
Disaggregated memory architecture has gained wide adoption in cloud and high-performance systems [18, 31, 43] due to its decoupled resource model, elasticity, and low-latency access. In such architectures, transaction mechanisms must ensure atomic and consistent access to remote memory. Prior designs use array-based version structures to improve locality, but their fixed capacity introduces false conflicts, especially for long transactions that require accessing historical versions, limiting concurrency and throughput. We present MiTDM, a transaction system tailored for disaggregated memory environments. MiTDM introduces a hierarchical block version chain that combines the benefits of array and chained structures, supporting dynamic version expansion while maintaining low-latency access. A lightweight Block Index Table accelerates remote reads, and an asynchronous index update mechanism synchronizes indexes across nodes with minimal overhead. To manage version growth, MiTDM employs a hybrid garbage collection strategy aware of transaction states, enabling safe reclamation and reuse of version slots, particularly in hot spots. A one-sided optimistic transaction protocol ensures consistency and atomicity under high concurrency. Experimental results on a disaggregated memory cluster show that MiTDM outperforms state-of-the-art systems. Under the TPC-C workload with 128 clients, it achieves up to 80.1% higher throughput compared to FaRMV2 and 42.7% higher than Motor, while significantly reducing P50 and P99 latencies.