SharPer: Sharding Permissioned Blockchains Over Network Clusters

TL;DR

SharPer is a permissioned blockchain system that enhances scalability by clustering nodes into data shards, efficiently supporting both intra-shard and cross-shard transactions with a novel consensus protocol.

Contribution

It introduces a clustering-based sharding approach with a DAG-based ledger and a flattened consensus protocol for cross-shard transactions.

Findings

Improves scalability in permissioned blockchains.

Efficient handling of cross-shard transactions.

Demonstrates performance benefits in workloads with low cross-shard activity.

Abstract

Scalability is one of the main roadblocks to business adoption of blockchain systems. Despite recent intensive research on using sharding techniques to enhance the scalability of blockchain systems, existing solutions do not efficiently address cross-shard transactions. In this paper, we introduce SharPer, a permissioned blockchain system that improves scalability by clustering (partitioning) the nodes and assigning different data shards to different clusters where each data shard is replicated on the nodes of a cluster. SharPer supports both intra-shard and cross-shard transactions and processes intra-shard transactions of different clusters as well as cross-shard transactions with non-overlapping clusters simultaneously. In SharPer, the blockchain ledger is formed as a directed acyclic graph where each cluster maintains only a view of the ledger. SharPer also incorporates a flattened protocol to establish consensus among clusters on the order of cross-shard transactions. The experimental results reveal the efficiency of SharPer in terms of performance and scalability especially in workloads with a low percentage of cross-shard transactions.