Data sharing with a Red Hat GFS storage cluster

by Marc Grimme, Mark Hlawatschek, and Thomas Merz of ATIX, Munich, Germany

This article is an updated version of an article first published in the April 2005 issue.

Introduction

Linux® server clustering is an important technique that provides scalable performance and high availability for IT services. These services quite often require that data be shared between servers. Even small companies often have many computers, including desktops and servers, that must share data. Hence, data sharing is a requirement for both small and large companies.

Some services have static data that can easily be copied between servers. In this scenario, each server in the cluster hosts its own copy of all the data. Other services utilize dynamic data that is rapidly changing, making it much more difficult to duplicate data between servers. For example, databases and file services (based on protocols like SQL, NFS or CIFS) would have to distribute the new information synchronously to all other servers after each write. This would lead to very long response times and an extremely high network load. Another disadvantage is the higher cost of maintaining duplicate copies and the associated increase in system management complexity.
What these applications really need is access to a single data store that can be read from and written to by all servers simultaneously. The use of a file server (network attached storage server) supporting the NFS and CIFS protocols is the traditional approach for this kind of shared data. Linux, of course, offers these popular data sharing protocols. This solution is suitable for some applications, but a single file server often becomes a performance bottleneck and single-point-of-failure in the complete system.

To use these traditional approaches for scalable and simplified data sharing, every server in the cluster should have direct access to the storage device and each server should be able to read and write to the data store simultaneously. ATIX developed such a solution--the com.oonics Diskless Shared Root Cluster. Red Hat® Global File System (GFS) is the basis of it.

Um den Artikel weiterzulesen, klicken Sie bitte hier