NonStop NS-Series Operations Guide (H06.12+)

Task 2: Find and Eliminate the Cause of the Problem
After you collect the facts, you are ready to begin considering the possible causes of a problem.
Using these facts and relying on your knowledge and experience, begin to list possible causes
of the problem.
Task 2a: Identify the Most Likely Cause
To evaluate the possible causes of any problem, you must compare each cause with the problem
symptoms. The problem-solving worksheet gives you a guide for accomplishing this task. In the
following example:
• Possible causes become column headings
• Entries made in the worksheet’s rows indicate whether the cause in that column could have
produced the problem symptoms you listed in that row.
— Write yes in the appropriate box if that cause could explain that symptom.
— Write no in the appropriate box if a possible cause does not explain a fact.
The most likely cause is the one that best explains all the facts; that is, the cause that contains
the most yes answers.
For example, possible causes of a hung terminal problem could be:
• A terminal hardware problem
• A stopped or suspended TACL process
• System security, which locks a user out after three unsuccessful logon attempts
This worksheet lists some possible causes of a hung terminal and illustrates further how to
evaluate the possible causes:
Possible CausesProblem Facts
SecurityTACL processTerminal hardware
YesYesYes
What?
Terminal $JT1.#C02 is hung
YesYesYes
Where?
Office of USER.BONNIE
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
No
When?
8:30 a.m. today
Two days ago at 8:30 a.m.
After 3 failed logon
attempts
Yes
Yes
Yes
Yes
?
?
Magnitude?
Intermittent
Goes away on its own
Task 2b: Fix the Most Probable Cause of the Problem
For the example in the worksheet, the most likely cause of the hung terminal is a security problem.
Ask yourself what would be the fastest, least expensive, safest, and surest way of verifying that
this is the most probable cause of the problem.
Once you have determined the most likely cause, try to fix it. Follow through and implement
the appropriate solution. If this solution does not fix the problem, continue trying other possible
solutions that are reasonable considering time, expense, and safety.
Determining the Cause of a Problem: A Systematic Approach 29