Using SANs and NAS

Author: W. Curtis Preston

ISBN: 0596001533

Publisher: O'Reilly

Reviewed by: Dean Wilson

While storage capacity has grown (almost as fast as the amount of data we want to store!) our ability to manage and backup critical resources has been lagging behind, and is only just emerging from the dark ages. Although a couple of 250GB hard drives and a DVD burner may be an adequate solution for a home user, a company with large databases, shared file servers, remote home directories and tight data recovery windows needs something more; this book presents the two best options.

Two main options exists for enterprise data storage needs: SANs and NAS. This book aims to provide an introduction, comparison and enough information to set you onto the path of efficient, trustworthy data access and storage using the most suitable of the two technologies. The book itself is broken up into three main sections: a brief overview of using fibre channel as a storage back bone, a look at storage attached networks (SANs) and a look at network attached storage (NAS).

The book opens with an overview of the two storage technologies and the uses to which each is best suited. After reading this chapter you'll know if you only need to read the SAN or NAS related chapters; although reading the whole book cover to cover isn't a chore. The second chapter is a short but very well written primer on fibre channel. It explains why you'd want to use fibre channel cabling in your storage architecture, shows the typical topologies, explains addressing and closes with a look at its relationship with storage technology.

The next two chapters make up the SAN section of the book, starting with "Managing A SAN" and then moving on to "SAN Backup and Recovery". These chapters take a reader unfamiliar with SANs on a tour of the benefits and issues with SANs before explaining the concepts of zoning, improving SAN availability (via some sample topologies) and the need for persistent binding of devices. SAN Backup and Recovery is a mixed chapter. It shows some of the major benefits available with a SAN (LAN free, client free and server free backups each get a lot of coverage) and explains when you should consider each. While the coverage is thorough and provides you with the background knowledge to make a simple evaluation of each benefit in the context of your own environment, the pace of this chapter didn't feel right and seemed to drag on.

The last section of the book covers NAS (in somewhat less detail than SANs were covered) and provides some interesting background on how NAS works, including details on a number of the performance gains. The second NAS focused chapter explains how NAS can fit in to your infrastructure, however it approaches the topic from a very high level so while the points are all worth considering there isn't really any meat in the answers.

The last chapter of the book looks at how to backup and recover NAS. Without getting in to any real technical depth it explains the more common techniques and shows a number of pitfalls inherent in using native tools before delving in to the more useful NDMP (network data management protocol); an open standard that provides a common way for backups to be executed.

I first read this book near its release date almost three years ago. On my initial read it took me from knowing nothing about SANs, NAS or basic fibre channel usage to being able to hold a sensible conversation with the consultants that were proposing a SAN based solution. After re-reading it three years later the book still serves as an excellent introduction to the technologies, terms and basic principles. While it's light on actual technical and implementation details, this has helped the book to age extremely well and it's still one of the best introductions to a confusing subject.

Summary: Excellent introduction to SANs, NAS and fibre channel that has aged well. 7/10