Advanced orthogonal RAID based on virtual disks

摘要

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. However, in order to construct large-scale storage, more than 3 fault tolerant (3FT) RAID is important. In the previous work we proposed 3FT orthogonal RAID named MeshRAID, which is not tolerant of only disk fault but also tolerant of string fault. In this paper, we propose MeshRAID MP (Multiple Parities), which employs multiple parity RAID. Especially, MeshRAID2P consists of 2 parities and 2 fault tolerant (2P–2FT) RAIDs such as RAID6. We compare MeshRAID2P implementations based on different 2P–2FT RAID with each other. In VLSD, there are 3 kinds of 2P–2FT RAIDs: RAID6 which has distributed P + Q parities, RAIDq which has dedicated P + Q parities, and RAIDd which has row parity and diagonal parity. We show that MeshRAID MP is more effective than multi dimensional MeshRAID.