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1. Self Service Linux

Mastering the Art of Problem Determination

1.1 4/5 Recommended for the Very Experienced User

Mark Wilding and Dan Behman
2006, Pearson Education, Inc, ISBN 0-13-147751-X
$55.99 USD

1.2 Surprise! Surprise!

I did not know what to expect I suppose. From the title it was obvious that this was going to be a book about troubleshooting. But I should have given the word "Mastering" the respect it deserves, especially when used in the title of the book!

1.3 Just a Little on the Basics and Then ....!!!

The first chapter I would recommend to just about anyone, beginner or advanced. It does a very good job of laying out the way to handle a new problem. You'll find out how to document information to support your problem case, how to seek help on the problem in a friendly way and how to separate symptoms of the problems from the actual cause of the problem. Chapter 1 is well worth the read even if the rest of this book goes completely over your head.

But after chapter 1 the pace of the book radically changes in favor of the very experienced user (some x86 assembler really helps). The rest of the book covers in great detail (emphasis on great) the inner workings of system call tracing with strace, gleaning information from /proc (some is basic stuff, but mostly advanced), compiling software, the Linux stack, GNU debugger (gdb), the kernel debugger (kdb) and the ELF executable format.

1.4 Strace

Just to give you a feel for the text and the amount of information it contains... and the reading level the author expects:

Notice the interrupt instruction: int $0x80 and the move (mov) instruction directly preceding. The move instruction moves the system call number 5 into the %eax register, and the interrupt instruction switches the current thread of execution into the kernel. This is where the actual instructions are for the open system call. A bit of grepping through the system header files shows that the system call in indeed open.

So... my guess is that will quickly weed out the beginner's and many intermediate reader's! However, for those looking for a book that does a pretty good job at explaining the inside technical details behind certain elements of Linux, this may be the book for you.

At the same time though, perhaps too much attention is given to the inner workings of things rather than the actual goal of "problem determination." The good elements about the latter are the ways the author shows how to use the options for strace to do things like determine the amount of time spent in a system call or the time used between system calls.

1.5 /proc

This chapter was the most reference like. Now there is extensive discussion with regards to process information, the rest are brief snippets about the items found in /proc. But it's not over simplified shallow content, I learned quite a bit from the brief synopsis of each item. You will likely learn something new about /proc reading this book.

A brief example from the /proc/sys/kernel section covering the core_pattern file:

This file is new in the 2.6 kernel, but some distributions such as SuSE have back ported it to their 2.4 kernels. Its value is a template for the name of the file written when an application dumps its core. the advantage of using this is that with the use of % specifiers, the administrator has full control of where the core files get written and what their names will be. For example, it may be advantageous to create a directory called /core and set the core_pattern with a command something like the following:

 penguin> echo "/core/p" > core_pattern

For example, if the program foo causes an exception and dumps its core, the file /core/foo.3135 will be created.

1.6 Compiling Software

This chapter covers the problems encountered when compiling from source. It includes user programs as well kernel compilation. You'll get to know more assembler and see how the optimizer deals with certain situations.

The end of the chapter says, "With more knowledge of problem determination at runtime, you're well on your way to becoming a completely self-sufficient Linux user." Ah... notice self-sufficient vs. the title's use of self-service. I hope you see why this book is certainly for the experienced user.

1.7 Enough Already!

I could go on and on... but with each chapter the authors present a very detail analysis of the subject matter with no fear of assembly language. If you really want to know how things work, this is a great book.

1.8 Ends Well

The appendices are excellent. Appendix A contains a list of troubleshooting tools and what they do. Very worthwhile! Appendix B contains a shell script that can be used to create a summary of information that might be relevant when presenting a potential problem.

1.9 Must Have for the Techie

I'll admit, this book takes awhile to go through. It's very detailed. But if you have a Mr. know-it-all in the family, here's a book that could put them in their place. I recommend this book for the very experienced user who wants to become completely self-sufficient in Linux.

If you expected a book for helping you in doing problem determination though, chances are this is not the book you were looking for. In my opinion, it's far too detailed. Maybe that's what is required to 100% accurate determinations, but in practice I find that a really, really good guess will often take you to the correct root cause.

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