  With the surge in cloud storage adoption, enterprises face challenges
managing data duplication and exponential data growth. Deduplication mitigates
redundancy, yet maintaining redundancy ensures high availability, incurring
storage costs. Balancing these aspects is a significant research concern. We
propose FASTEN, a distributed cloud storage scheme ensuring efficiency,
security, and high availability. FASTEN achieves fault tolerance by dispersing
data subsets optimally across servers and maintains redundancy for high
availability. Experimental results show FASTEN's effectiveness in fault
tolerance, cost reduction, batch auditing, and file and block-level
deduplication. It outperforms existing systems with low time complexity, strong
fault tolerance, and commendable deduplication performance.
