Review of Using SANs and NAS

Using SANs and NAS
W. Curtis Preston
O'Reilly and Associates

Reviewed by Nick Christenson,

November 13, 2002

The amount of data stored by a typical organization has grown at a fantastic rate. Largely because they can, people are collecting, saving, and analyzing information about anything and everything. Even as disk capacities have grown almost as fast as our voracious appetite for information, developing increasingly more sophisticated methods for managing this information have become a necessity. Often, these solutions are categorized into "Storage Area Networks" (SANs) and "Networked Attached Storage (NAS), but the best way to take advantage of these technologies is not always clear. To address this, Curtis Preston has written the book, Using SANs and NAS.

The book starts with a basic description of these technologies. The author considers the key difference between them to be whether the file access protocol is block-level for SANs (such as when accessing a direct-attach disk) or whether there exists a file abstraction as in NAS (such as in NFS). This is a reasonable way to distinguish between the two terms, although it's not the method I use.

Next, the author describes SAN issues, starting with a Fibre Channel overview and moving into topics such as SAN management and the ever-popular morass of SAN backups. The Fibre Channel overview is sufficient for most folks, but I was surprised that the author didn't refer the readers to other sources for more detail. The author's discussion of SAN management is reasonable, but light on details. The reader is advised of some aspects that deserve attention, but the book is pretty light on real-world examples. Preston's categorization and description of SAN-based backups is quite good, though, and may clarify things for readers who may be confused on the topic. Again, I wish he had named names and pointed at specific vendor products more than he did, but I understand why this wasn't done.

The rest of the book is devoted to NAS issues. The author starts with a description of why NAS devices may be preferable to traditional NFS, SMB, etc. file servers. The reasons are well thought out, but here, and in other places, the book occasionally reads more like an industry advertisement than I'd prefer. Preston then moves on to NAS management and NAS backups. These sections are less detailed than the SAN chapters on the same topics, mostly because of the nature of the NAS devices. Data management systems are typically integrated into the NAS devices themselves, meaning that the user typically has less to think about here, although often less choice as well.

While the book does a credible job of explaining these technologies to the reader, I'm somewhat disappointed that the author doesn't go any further than he does. The issue of SAN data sharing through the use of clustered filesystems isn't discussed at all. Also, there are no examples any more detailed than those found in vendor brochures. At just over 200 pages, this is a pretty thin book. I certainly don't think it would be a waste of space to discuss some real-world detailed case studies. Regarding whether NAS or SAN solutions are applicable to a particular problem, I can't say that I found the author's advice to be particularly useful. Again, I believe that some detailed examples would be more than useful. I fear that people will read this book, understand the core technology, but be little better off in terms of solving their real problems.

Using SANs and NAS provides a good description of these interesting technologies as far as it goes. The main downside with this book is that it doesn't go very far. This book is well written and will be extremely useful for those who want a foundation in these technologies, and it will help the reader sort through the maze of information and disinformation provided by many vendors. It will not, however, provide a lot of useful information on how to design and develop a particular IT infrastructure to solve real-world problems. If a basic understanding is desired, then the reader will be well-served by Using SANs and NAS.


Using SANs and NAS provides a good foundation on these two technologies, including a reasonable comparison between them. On the other hand, there is little information here on how to apply these technologies toward solving specific problems. Therefore, I recommend this book as far as it goes, but I would have preferred if it had gone farther.

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