HerpRap: A Hybrid Array Architecture Providing Any Point-in-Time Data Tracking for Datacenter

Both physical disk failure and logical errors such as software error, user abuse and virus attacks may cause data lose. The risk of logical errors is far greater than physical disk failure. Moreover, existing RAID solution cannot satisfy the reliability requirement in face of the logical errors in data centers. It is therefore becoming increasingly important for RAID-based storage systems to be able to recover data to any point-in-time when logical errors occur. We proposed a novel storage array architecture, Herp Rap, which is able to recover data from both physical disk failure and logical errors. We have implemented a prototype of Herp Rap and carried out extensive performance measurements using DBT-2 and file system benchmarks. Our experiments demonstrated that the proposed Herp Rap is able to track or recover data to any point-in-time quickly by tracing back the history of block logs. Moreover, Herp Rap outperforms existing HDD-based or SSD-based RAID5 with copy-on-write (COW) snapshot in terms of performance, energy efficiency, failure recovery ability and reliability.