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Identifying Problems

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The usual method of identifying problems is to characterize the situation in which the problem occurs and then investigate which of the possible causes are actually responsible for the problem. Finding the cause is often sufficient to suggest the resolution of the problem. For example, assume that the problem is characterized as "the user is unable to open a line with the DSLINE command." A possible cause is that the user entered a command using incorrect syntax. You would resolve the problem by correcting the command and reissuing it. However, if the syntax was correct, you would have to look for another possible cause, such as an inactive link or a failure of the remote node.

Thus, in most cases you start with the characterization of the problem and investigate the possible causes. The difficult part of troubleshooting is to identify the actual cause of the problem. Once you know the actual cause, you can take the appropriate action to resolve the problem.

Characterize the Problem

It is important to ask questions when you are trying to characterize a problem. Start with global questions and gradually get more specific. Depending on the response, you ask another series of question, until you have enough information to understand exactly what happened.

Key questions to ask are as follows:

  1. Was an error message generated? Use the NS 3000/iX Error Messages Reference Manual to look up the cause of the error and take the action suggested. If this does not resolve the problem, continue with the next question.

  2. Is the problem isolated to one user or program? If so, continue to the next question. If more than one user is involved, proceed to question 6.

  3. Did the user perform the operation correctly? Was syntax correct? Does the user have the correct logon and authority to use the command or service? Correct any problems found. If the operation was correct, continue with the next question.

  4. Did the problem occur while the user was running a program? Were there program errors? If so, investigate and correct the program errors. Otherwise, continue with the next question.

  5. Did the problem occur while attempting to open a line or transmit data? If so, investigate the connection between this system and the remote system.

  6. If more than one user is involved, does the problem affect all users? The entire node? If so, has anything changed recently? Some possibilities are:

    • New software and hardware installation.

    • Same hardware but changes to the software. Has the configuration file been modified? Has the MPE/iX configuration been changed?

    • Same software but changes to the hardware.

  7. Do you suspect hardware or software?

    It is often difficult to determine whether the problem is hardware or software related. Symptoms that mean you should suspect the hardware are:

    • Bad LAN card or PSI dumps.

    • Link level errors, either returned to the user or logged to the console. This includes CI errors, NMERR errors, power fails, and link shutdowns.

    • Lost data — data is sent but not received at the link destination. (This could also be caused by a software problem.)

    Symptoms that mean you should suspect the software are:

    • Logging messages at the console.

    • Network Services errors returned to users or programs.

    • MPE/iX file system (FSERR) or command interface (CIERR) errors (except "Remote Not Responding" errors).

    • Data corruption.

    • Terminal hangs.

    • Intermittent errors.

    • Network-wide problems.

Identify the Cause of Problems

The type of investigation that you use to identify the possible causes of a problem depends on whether the problem affects one user or an individual situation, or if the problem is node-wide. Once you have the answers to the questions listed previously, use the flowchart in Figure 4-1 "Characterizing the Problem" as a guide and see Chapter 5 "Common Network Problems" for a problem resolution strategy.

Figure 4-1 Characterizing the Problem

[Characterizing the Problem]



Chapter 4 Troubleshooting Process

Chapter 5 Common Network Problems