6.4.1.2 Direct changeover
The old system is stopped and the following day the new system
is used. This could be disastrous if there are errors in the new system.
With this strategy, the changeover is done in one operation,
completely replacing the old system in one go. This usually takes place
on a set date, often after a break in production or a holiday period so that
time can be used to get the hardware and software for the new system installed
without causing too much disruption.
Advantages:
i) The most rapid of all the strategies, provided it works.
ii) Less risk of confusion between old and new systems.
Disadvantages:
i) Most stressful for the users - the old system has gone so
there is no going back if they have difficulties.
ii) Most difficult to train staff on as the new system was not
in place to learn before the changeover.
iii) Most stressful for the developers - all the data and
files from the old system will have to be converted ready for use on the new
one.
iv) Most risky - if the new system does not work properly then
there is nothing to fall back on.
6.4.1.3 Pilot
running
The new system could be tried by part of the company such as
one branch.
If all goes well, then the rest of the company can change to
the new system
With this strategy, the new system replaces the old one in one
operation but only on a small scale. For example it might be tried out in
one branch of the company or in one location. If successful then the
pilot is extended until it eventually replaces the old system completely.
Advantages:
i) Easy to control, the pilot can be halted at any time.
ii) Easy to evaluate because the new and old systems are both
running.
iii) Low risk, if a small-scale pilot fails then not too much
has been lost.
iv) Easy to train staff by letting them learn new skills on
the pilot system.
Disadvantages:
i) It can be slow to get a pilot to completely replace the old
system.
ii) A pilot may not show up problems that a full-scale
implementation would. This is because a system can work well as a small-scale
pilot but has difficulties when it is scaled up to a full operating system with
more realistic volumes of data to be processed.
6.4.1.4 Phased
changeover
With this strategy, the new system is brought in in stages
(phases). If each phase is successful then the next phase is started,
eventually leading to the final phase when the new system fully replaces the
old one.
Advantages:
i) Very structured, each phase can be fully evaluated before
moving onto the next one.
ii) Lower risk, a well-planned and controlled introduction of
the new system.
iii) Easy to train staff by letting them to learn new skills
on each phase as it is introduced.
Disadvantages:
i) Slower than direct implementation.
ii) Although each phase is easy to evaluate, you have to wait
until all the phases are complete before you can evaluate the whole change
over.
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