August 1999
IM218 :INFORMATION MANAGEMENT

QUESTION 4

Total Marks: 20 Marks

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(a) Discuss two reasons for carrying out system performance evaluation. [2]
  • System performance evaluation is needed for system planning, which is facilitated by knowledge of how the system is performing.
  • Performance evaluation can provide information on whether equipment should be replaced, or whether the current equipment should be reconfigured to meet objectives better.
  • Performance evaluation is also used as a preventative measure.

 
(b) System modelling is one of the steps performed in the system evaluation process.

(i) Briefly describe the three activities involved in system modelling.

(ii) Describe the three different types of system model that can be produced in system modelling.

  


[3]

[3]
(i)
Defining the system boundaries:
It is necessary to define formally exactly what is to be evaluated.

Identifying system attributes:
The next step is to identify the various characteristics or attributes of the system components or entities.

Constructing a causal diagram:
This depicts the cause-and-effect relationships that exist within the model.

 
(ii)
Informal model:
consisting of assumptions, biases and experience of the modeller as they relate to the system being represented;

Queuing model:
an analytical model, viewing each entity in the system as a server, receiving requests for and granting service to programs;

Simulation model:
involving the depiction of the system in various stages of change, then alternating the simulation to optimize the results.

 
(c) Why is hardware maintenance important? [2]
Computer hardware consists of physical devices; if they are not maintained, they can break down and disrupt service.

 
(d) Briefly describe the following four hardware maintenance schemes.

(i) Internal service

(ii) Manufacturer's maintenance agreement

(iii) Third-party services

(iv) Combined services

 [4]
(i)
A service department to maintain hardware can be set up within the organization.

 
(ii)
For a fixed fee, a manufacturer agrees to repair most equipment malfunctions during specified hours of the day; alternatively, the organization might be charged per occasion.

 
(iii)
It is quite common for third-party firms to stock spare parts for big customers, helping to speed repairs.

 
(iv)
For example, to entrust major problems to the manufacturer or third party, while internal staff deal with minor problems.

 
(e) Which hardware maintenance scheme would be appropriate for a company with 1000 personal computers, and which for a computer with just 1 personal computer? [1]
Only an organization with many computers can afford to run an internal service department; a smaller organization must contract out maintenance.

 
(f) Why might third-party service be preferable to a manufacturer's maintenance agreement? [1]
It is likely to be cheaper.

 
(g) Why is software maintenance more complicated than hardware maintenance? [4]
Although software does not wear out, its environment and hence its requirements change. As changes are made, the structural coherence of the software deteriorates. Software systems can be surprisingly long-lived; it may have originally been developed using out-of-date methods and languages and the people who developed it may no longer be employed by the organization.