The Book of Xen [Paperback]

I've read this book as well, and I can say I absolutely LOVE it. I'm not sure if I agree with the other reviewer's analysis of the book, it seems like he comes from a non-technical background and prefers to want to know all the reasoning behind certain ways to do a proper Xen setup. I've been using Xen for the last 1.5 years and I can say this book is absolutely essential for anyone using Xen on 2 or more computers. I own a mini cloud with my own miniature cluster of Xen instances (roughly 60 virtual machines), and it's hard to get things right if you're unfamiliar with all the tools that Xen offers. For example, "The Book of Xen" makes it easy and straightforward for doing backups using LVM, with everything down to the exact command needed to run at the prompt.

It also has a great chapter on running Xen on alternative operating systems like Solaris. It took me about 10 hours of searching through tutorials on the net to figure out how to get Solaris to properly install on a Xen instance. I'm using OpenSolaris on Xen for my personal home backups so that they can run on the popular ZFS filesystem using raidz. The tutorials on the internet are mostly wrong and incomplete, but the step by step instructions in the book made it quite easy.

I also loved the chapter on Xen migration, something I've been doing pretty poorly and haphazardly using various scripts of my own. Although I'm pretty confident at the Linux command line, there are a few things I didn't know about how to run a proper Xen migration. I especially liked the section about live migration -- most of my friends running Xen on their colocated servers don't know this subject well and could probably learn a thing or two by reading this chapter.

There's also a cool chapter on running Windows XP on Xen. I've been trying to get multiple XP instances running under my Xen infrastructure so that I could run my Selenium integration test suite under a native IE8 web browser, but so far it has been really hard. I'm really happy the book distills the painful parts of the set up process in just one chapter.

Most of the time Xen "just works", but I'm glad the book has a good chapter on troubleshooting Xen issues. I've run into a bunch of these issues when trying to boot my OpenSolaris instance under Xen and without the book's troubleshooting recommendations, I probably would have been stuck for hours on the problem.

This book is great for anyone who just wants to get things done, it's not a book to learn about the internals of Xen. I'd recommend Mr R. Kolodziej to buy a book about basic Linux system administration before reading "The Book of Xen". Anyone installing xen-tools on Debian will probably know what their doing and will be the perfect reader for this book. If you don't know Linux well enough, I would recommend reading Mr Nemeth's well regarded "Linux Administration Handbook" before reading this one.

The Book of Xen (TBOX) is a great book for Linux system administrators who want to deploy Xen. The authors ground their recommendations in over four years of experience running Xen to support Internet-facing virtual private servers. I found their writing style to be very engaging; it reminded me of reading any one of Michael Lucas' No Starch books. If you know your way around Linux and want to deploy Xen in production, TBOX is the book for you.

About two years ago I read and reviewed Professional Xen Virtualization by William Von Hagen. That book spends more time guiding the reader through the concept of virtualization, and tends to cover system administration from a wider angle than TBOX. In contrast, TBOX treats the reader more as a professional sys admin who wants to apply his or her skill set to Xen. TBOX does spend some time discussing Xen internals, and I found the depth of that discussion just right for this book. Other books discuss Xen internals to a greater degree, so there was no need to repeat material here.

TBOX does tend to focus on running Linux domU on a Linux dom0. This is not surprising given the lesser maturity and popularity of other options, specifically as dom0. Ch 8 does cover Solaris and NetBSD, and Ch 13 is devoted to Windows as domU. As support for Xen matures I expect a second edition of TBOX to address other combinations of operating systems as dom0 and domU.

TBOX is unique thanks to the sections on profiling and benchmarking (Ch 10), "tips" (Ch 14), and troubleshooting (Ch 15). I appreciate when authors of technical books share lessons and tricks from their own shops. I am also a big fan of their writing style and attempts at humor. This could easily have been a very dry technical book, but TBOX is entertaining from the start. Great work!

Most Xen documentation on the Internet can be a tad focused on the single-computer, single-admin personal-use xen administration case. This book, thankfully, is not.This is definitely the book to keep on your shelf if you require tips and tricks for setting up your own VPS hosting service, with its world full of malevolent users needing to be kept in their place, quotas for bandwidth, disk I/O, CPU time, and memory usage, and allowing your users to configure their own instances without you having to step in every time they blow out their /boot partitions.

There are plenty of concepts covered in here for other use-cases (besides just hosting your own VPS provider) as well, including remote-mounting disks over NFS/iSCSI/AoE, migrating live Xen instances across a cluster of servers, and backing up disk images and machine states.

The Book of Xen provides a fair and balanced view of Xen management; that is to say, while it it does talk often about the many distro-specific ways of easily bootstrapping and configuring a new virtual server (like Debian's debootsrap, Red Hat's virt-install, or even creating images in Citrix XenServer) it also covers vendor and distro-neutral ways of performing all the required installation and management tasks. The Book of Xen is also fair in that it also goes on to describe the use and configuration of Microsoft, BSD, and Solaris Xen dom0 and domUs as well, with the caveat that support for Xen is weak and upcoming on such platforms as FreeBSD, and that HVM is required for many of these more exotic operating systems like "Microsoft Windows", as there are no Xen hooks in the Windows kernel.

I particularly liked the Book of Xen's first chapter, which, unrelated to the rest of the book's sysadmin-oriented content, was a good overview of the technical underpinnings of the Xen hypervisor platform, and how it interacts with the hardware and virtualized machines from a very low-level perspective. As it is stated later in the book, and something that I agree with, the authors believe that one must know a technology, how it works, and its more basic manual and command line tools, before ever trusting a GUI or web interface to do the same. It will also surely aid debugging later when something goes wrong, as the administrator will have a good idea as to where the problem might lie.

All in all, I liked the book and would recommend it to anyone setting up their own Xen servers, however, I wished it would have had more information about Xen on the Intel Itanium (which is touched upon in the book as being a supported platform, but not talked about further) and I wish it had talked more about some of the topics they covered, like giving users access to their own xen management consoles, in the common situation where there are many physical machines that a user's instance could be on, a situation which completely broke their offered solutions for this situation and others.