Research on Storage Arrays Global Cache Technology Based on CXL

Global cache is a core technology for enterprise-grade storage arrays, whose primary function is to improve data write performance. I/O operations return immediately once data is written into the memory cache of storage controllers, without waiting for the data to be persisted to slow HDDs or SSDs. However, the design of global cache in enterprise-grade storage products must comprehensively consider factors such as the number of replicas, system high availability, and failure scenarios. Constrained by the mutual interactions of these factors, the number of controllers in storage clusters typically cannot exceed 4, and system high availability fails to support the scenario where 3 out of 4 controllers fail concurrently. Furthermore, the transmission of cache replica data between controllers via RDMA technology also impairs storage performance. Thus, a memory-disaggregated global cache system prototype is designed based on the latest CXL technology. With memory cache disaggregated from within controllers to external, the system offers three key advantages: first, controllers and memory cache can scale out independently, supporting multiple cache replicas; second, controller failures do not cause cache data loss, supporting concurrent failures of n-1 out of n controllers; third, CXL technology significantly optimizes storage performance while enhancing system scalability and high availability. Experimental results demonstrate that the CXL-based global cache achieves a 38% performance improvement compared with the RDMA-based global cache.