Balancing Reliability and Cost in Cloud-RAID Systems with Fault-Level Coverage

Abstract

Based on redundancy techniques, cloud-RAIDs (Redundant Array of Independent Disks) offer an effective storage solution to achieve high data reliability. Their performance however can be greatly hindered by the fault-level coverage (FLC) behavior, where an uncovered disk fault may crash the entire system in spite of adequate redundancy remaining. Moreover, different choices of cloud disk providers lead to designs with different overall reliability and cost. Thus, in this paper we formulate and solve optimization problems, which determine the combination of cloud disks (from different providers) maximizing the cloud-RAID system reliability or minimizing the total cost. The cloud-RAID reliability is analyzed using a combinatorial and analytical modeling method while considering effects of the FLC behavior. Multiple case studies are performed to demonstrate the considered optimization problems and proposed solution methodology.