In-network aggregation enabled multiple sub-blocks parallel repair in erasure-coded storage system

Erasure coding has gained widespread adoption in large-scale distributed storage systems since it can significantly reduce storage overhead while ensuring high reliability. However, repairing failed data in erasure-coded systems requires retrieving data from multiple nodes, which generates substantial network traffic, and often leads to incast congestion and degraded repair performance. Existing solutions alleviate requester-side congestion by offloading aggregation operations to helpers (nodes that provide repair data), but they inevitable increase inter-helper traffic and still struggle to fully utilize global network resources. To this end, we propose lnaPR (In-network Aggregation Enabled Parallel Repair for Multiple Sub-Blocks), a framework that leverages programmable switches to perform in-network aggregation during data repair. InaPR decomposes a data repair task into multiple tree-structured pipelines, enabling data repair to collect source data from more helpers beyond the fixed k-nodes requirement. Then, the bandwidth allocation for each pipeline is optimized through a two-stage methodology: (1) a heuristic helper allocation strategy that assigns high-bandwidth helpers across multiple pipelines while distributing low-capacity ones among distinct pipelines; (2) a throughput-maximizing bandwidth allocation formulated as a linear programming model. Furthermore, we also extend the architecture to cross-rack scenarios through virtual node decomposition. Finally, we prototype lnaPR using a P4-programmable switch and validate its performance in real-world evaluations and multi-rack simulations. Experimental results demonstrate that InaPR achieves 6.74% higher repair throughput than state-of-the-art methods in single-rack prototype tests and an 11.03% improvement in cross-rack simulations.