The Open Source Samba [1] system has provided file and print services for Windows and Unix-style computers since 1992. The Samba developers [2] always had difficulties emulating Windows server characteristics without the specifications, but thanks to Microsoft finally releasing the server protocol specifications late in 2007 [3], the task is now easier.

A recent add-on tool dubbed CTDB [4] now provides Samba with a feature that even Windows does not support: clustered file servers. Samba now offers the option of a distributed filesystem with multiple nodes that looks like a single, consistent, high-performance file server. And this cluster-based file server system is (more or less) infinitely scalable with respect to the number of nodes. (Windows 2003 does have some support for clustering, but it is designed with web and database servers in mind and restricted to eight nodes.)

In this article, I describe some of the the problems Samba solves with clustering, and I take a look at the history and design of the CTDB add-on at the center of Samba's clustering support. In addition, you'll get some hints on how to configure CTDB and set up your own Samba cluster.

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