6.4 System
implementation
After thorough testing by the programmers, the system is then
implemented into the working environment, replacing the original system.
6.4.1 System change over
System changeover is the process of putting the new
information system online and retiring the old system. There are four
strategies that can be used to do this:
(i) Parallel running
(ii) Direct changeover
(iii) Pilot running
(iv) Phased changeover
6.4.1.1 Parallel
running
The old system and the new system are run together for a
period of time. The old system is stopped only when it is certain that the new
system is running correctly.
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With this strategy, the old and the new system are both used
alongside each other, both being able to operate independently. If all goes
well, the old system is stopped and new system carries on as the only
system.
Advantages:
i) If there are initial problems with the new system then the
old one can still be used.
ii) Both systems can easily be compared.
iii) Easy to train staff by letting they learn new skills on
the parallel system.
iv) Easy to evaluate because the new and old systems are both
running.
Disadvantages:
i) Expensive - both systems are being run as fully operating
versions so both are doing the same job. This may mean duplication of
staff and hardware.
ii) Risky - there is a greater chance of confusion or errors
if the two different systems are being run side-by-side.
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