Problem Solving and Troubleshooting in AIX 5L - IBM Redbooks

1.1 Problem determination process
For the purposes of this redbook, a problem can be considered as any situation
where something that was previously working correctly is now not working as
expected.
1.1.1 Defining the problem
The first step in problem resolution is to define the problem. It is important that
the person trying to solve the problem understands exactly what the users of the
system perceive the problem to be. A clear definition of the problem is useful in
two ways. First of all, it can give you a hint as to the cause of the problem.
Secondly, it is much easier to demonstrate to the users that the problem has
been solved if you know how the problem is seen from their point of view.
Take, for example, the situation where a user is unable to print a document. The
problem may be due to the /var file system running out of space. The person
solving the problem may fix this and demonstrate that the problem has been
fixed by using the df command to show that the /var file system is no longer full.
This example can also be used to illustrate another difficulty with problem
determination. Problems can be hidden by other problems. When you fix the
most visible problem, another one may come to light. The problems that are
unearthed during the problem determination process may be related to the one
that was initially reported, in other words, multiple problems with the same
symptoms. In some cases, you may discover problems that are completely
unrelated to the one that was initially reported.
In the example described above, simply increasing the amount of free space in
the /var file system may not solve the problem being experienced by the user.
The printing problem may turn out to be a cable problem, a problem with the
printer, or perhaps a failure of the lpd daemon. This is why understanding the
problem from the users perspective is so important. In this example, a better way
of proving that the problem has been resolved is to get the user to print their
document.
1.1.2 Gathering information from the user
The best way of understanding the problem from the users’ perspective is to ask
them questions. From their perception of the situation, you can deduce if in fact
they have a problem, and the time scale in which they expect it to be resolved.
Their expectations may be beyond the scope of the machine or the application it
is running.
Chapter 1. Problem determination introduction 3