The Case for RAID 4: Cloud-RAID Integration with Local Storage

The proliferation of the Internet of Things (IoT) requires innovative solutions for all aspects of computing, including storage. The small footprint of IoT devices limits their capacity for local reliable storage. A solution is presented which combines local and cloud storage in a RAID-like (Redundant Array of Independent Disks) configuration, increasing the amount of storage, access speed, and/or data reliability and availability for systems which implement the discussed configurations. Previously, cloud-RAID, where data is distributed across multiple cloud storage providers, has been proposed and implemented. However, the current architectures place an emphasis on RAID 0, and other levels of RAID with their application to cloud storage have not been thoroughly explored. A novel architecture for local+cloud-RAID storage is presented, and benefits provided by the architecture in the areas of availability, reliability, and security are discussed. An effort to quantify the reliability of various configurations of RAID, cloud-RAID, and hybrid local+cloud-RAID levels will be made. While RAID 4 has been widely regarded as obsolete and supplanted by RAID 5, we argue that RAID 4 can be useful in a local+cloud-RAID configuration. A new RAID level based on RAID 4, with the addition of a second dedicated parity drive, is proposed, and is deemed RAID 4.5. We conclude that cloud storage, from the perspectives of availability, reliability, security, and performance, is beneficial to include in various RAID configurations which include local drives.