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Cluster based Mirroring using Redundant Arrays of Inexpensive Disks

IP.com Disclosure Number: IPCOM000237833D
Publication Date: 2014-Jul-16
Document File: 3 page(s) / 41K

Publishing Venue

The IP.com Prior Art Database

Abstract

In this article a method is described that expands error correction methods within a Redundant Array of Inexpensive Disks (RAID) on a single controller or storage system to a Shared Nothing (SN) architecture across multiple server nodes within a cluster where data is stored on local disks. A SN architecture does provide better scalability of the overall system compared to a centralized storage system which is especially important for Big Data applications deployed on cluster architectures.

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Cluster based Mirroring using Redundant Arrays of Inexpensive Disks

Redundant Arrays of Inexpensive Disks (RAID) [1] are built using disks attached to a single controller or to controllers comprised in a single server system or storage subsystem. In a server cluster with data stored locally on the server nodes with such RAID protection, the system would be protected against disk fails, but not against server node fails. Usually, central storage is used with such clusters that implement a local RAID on a storage server. With Shared Nothing (SN) architectures [2] only local storage is used that needs to be protected against disk and server fails. Disclosed here is a method to provide such RAID distributed across server nodes using the functionality of a cluster filesystem like IBM's General Parallel File System (GPFS) [3].

GPFS supports SN architectures with the File Placement Optimizer (FPO) [4] feature, where the local storage subsystems are comprised under one cluster filesystem. It does support data locality, i.e. data that is accessed local to a node is stored on local disks. It does also provide replication, i.e. within the filesystem data can be replicated. With such replication, it can be ensured that all replicated data is to be stored on distinct cluster nodes so that in case of a node failure, it can be ensured that a copy of the data is to be found on the remaining nodes.

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Figure: Cluster implementation using a Shared Nothing storage architecture with replication for production

In the Figure it is shown how the storage is distributed across several nodes, the data is stored locally within the first replica and a second replica is provided to prevent the overall cluster system against failures, i.e. providing high availability for such production filesystem. By doing that, in case of a server nodes outage in the cluster, all data is maintained within the cluster, i.e. a full mirror of the data is being provided across the cluster. This can be com...