Design and Implementation of 3D MeshRAID in Virtual Large-Scale Disks

Abstract

Recently, the demand of low cost large scale storages increases. We developed VLSD (Virtual Large Scale Disks) toolkit for constructing virtual disk based distributed storages, which aggregate free spaces of individual disks. However, in order to construct large-scale storage, more than or equal to 3 fault tolerant RAID is important. In the previous work we proposed Mesh RAID that is 3 fault tolerant orthogonal RAID. And, we implemented Mesh RAID using VLSD. Mesh RAID is a hierarchical RAID that shares elemental disks. The structure of hierarchical RAID is tree but the structure of Mesh RAID is DAG(Directed A cyclic Graph). Mesh RAID is not tolerant of only disk fault but also tolerant of string fault. Furthermore, in hierarchical RAID, the larger the number of layers is, the higher the reliability of the system. In Mesh RAID, increasing the layers is equivalent to increasing the dimensions. In this paper, we implement 3 dimensional Mesh RAID and evaluate it.