Blockchain technology has a great potential for improving efficiency, security and privacy of Electronic Health Records (EHR) sharing systems. However, existing solutions relying on a centralized database are susceptible to traditional security problems such as Denial of Service (DoS) attacks and a single point of failure similar to traditional database systems. In addition, past solutions exposed users to privacy linking attacks and did not tackle performance and scalability challenges. In this paper, we propose a permissioned Blockchain based healthcare data sharing system that integrates Blockchain technology, decentralized file system and threshold signature to address the aforementioned problems. The proposed system is based on Istanbul Byzantine Fault Tolerant (IBFT) consensus algorithm and Interplanetary File System (IPFS). We implemented the proposed system on an enterprise Ethereum Blockchain known as Hyperledger Besu. We evaluated and compared the performance of the proposed system based on various performance metrics such as transaction latency, throughput and failure rate. Experiments were conducted on a variable network size and number of transactions. The experimental results indicate that the proposed system performs better than existing Blockchain based systems. Moreover, the decentralized file system provides better security than existing traditional centralized database systems while providing the same level of performance.