Abstract
Cloud-RAID (Redundant Array of Independent Disks) is a data storage model, where different data redundancy techniques (corresponding to different levels) are utilized to enhance data reliability and availability in an anytime, anywhere data access framework implemented in the cloud environment. Such a fault-tolerant system can be subject to imperfect coverage due to imperfect fault detection or recovery mechanism, causing extensive damage to the whole system. In this paper, we model reliability of a cloud-RAID 6 storage system addressing effects of two types of imperfect coverage (element level coverage and fault level coverage). Numerical results are provided to illustrate effects of those behaviors on the system reliability performance.