Customer Reviews

User Mode Linux®

5 star:		(1)
4 star:		(1)
3 star:		(1)
2 star:		(0)
1 star:		(1)

 

 

I've read several of the books in Bruce Peren's Open Source Series, and this is by far the best. I read it cover-to-cover and enjoyed the author's relaxed and informative writing style.

The book does a good job of describing UML configuration options and facilities. But where it really shines is in the ancillary material, covering the whys and hows of other subsystems that work in conjunction with UML. For example, I found the treatment of network trouble-shooting that is interspersed with the UML networking section to be very well-done and useful beyond UML alone. Another high point is the information about kernel memory management (in conjunction with the discussion of tt, skas0 and skas3). But by far, the most enjoyable and impressive section of the book is the last two chapters in which the author challenges the reader to think about the wider implications of OS virtualization - for example why you might want to embed an instance of Linux inside another application that is in turn running on Linux (or even inside another UML).

I agree with the comment made by another reviewer that it would have been helpful to spend more time covering how to bootstrap a UML instance. (Hint: Chapter 1.5 - The transition between chapter 1 and chapter 2 is somewhat abrupt.) However, there are numerous other resources covering how to get UML running initially, and the author more than makes up for this short-coming with other (and in my opinion, more interesting) topics.

In summary, it's much more than just another dry, narrowly-focused subject treatment, and I found the author's style and open discussion of design decisions refreshing.

User Mode Linux (UML) is one of several virtual operating system technologies offered today. Most of these technologies emulate a physical piece of hardware. On that hardware, an operating system of choice can be loaded. UML is different in that instead of creating a virtual piece of hardware, UML creates a virtual operating system.

ABOUT THE BOOK

The book consists of thirteen chapters. The first few chapters are a good overview of UML, covering the basics of creating and accessing a virtual instance of a linux operating system. The middle chapters go deeper into UML configuration, covering network configurations, multiple network interfaces and managing all of these virtual operating systems from the central host. The final chapters cover more advanced topics, compiling UML from source, performance tuning considerations, and examples of different ways to use UML. There is even a section on how to build a cluster of virtual linux servers using Oracle's ocfs2. An extremely interesting idea for companies or groups who would like to try out a cluster configuration without having to make a large investment in hardware.

PROS

I found this book interesting and filled with good information. It helps that the author of the book is also the creator of UML. It was nice to see a lot of information on not only how to do something, but also the reasons why things were done they way they were. I would recommend the book for anyone interested in virtualization technology in the open source arena.

CONS

There is not a lot of comparison to all of the other similar technologies like Vmware or Xen. I would not recommend this book to someone wanting to choose between the different technologies.

UML is a great tool for all sorts of applications and projects, but the biggest attraction for me is the opportunity to learn more about the Linux kernel itself.

This book covers UML in depth, but also includes the thinking process Jeff Dike went through in its development and discusses the mistakes and trade-offs he made. You'll learn quite a bit about the kernel just from reading this and of course once you have it running, you can learn even more.

I thoroughly enjoyed this. My only complaint is that the book assumes your Linux came with UML installed and doesn't even tell you what RPM you need if it didn't - it's user_mode_linux and you can find that and everything else you need at [...]

I'll admit, I am a bit new to power Linux but I consider myself competent. The essential problem with the book is Jeff tries to present examples without any background or information. In chapter 3, the book jumps right into configuring UML from the host using 'uml_mconsole' withot telling the reader where to get it or how to compile it. This coupled with the lack of web resources associated with the book, makes it very hard to keep rolling with lessons.

Another example is the use of tap interfaces. tap interfaces don't just automagically appear when you start a linux box, they must be configured. Jeff makes no attempt to eductate the user on how to accomplish this and has no resource to go to for help.

I am using CentOS4 with kernel 2.6.9-34. Perhaps not the most up-to-date version but it should be adequate. I would have expected to find some pointers to usable kernels and root filesystems with which to experiment. Instead I find I spend most of my time fetching kernels and packages and building what I need, not by instruction in the book, but by info found through a Google search.

Who edited this book anyway? Did you even bother to try some of the "lessons" Jeff provided. I don't care that Jeff created UML, he doesn't hack it as an author. Spend your money on hookers and booze, the experience will certainly be more satisfying.