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Module 1: A fase de execução

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A Fase de Implementação: desenvolver um planejamento de implementação

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XSIQ
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Information Technology - The Implementation Phase: developing an
implementation schedule

The Implementation Phase: developing an implementation schedule

Image. Cutover, pilot, intermediate, phased, parallel, time.

Once all of the elements of the new system are in place, the next step is
to develop the implementation schedule (or cutover), and finally to cut
over to the new system. Most systems have a staggered introduction - that
is, elements of the system are introduced one at a time so that it is
possible to ensure that they are working as intended before the next
element is introduced. This is a common approach as it allows the
developers to quickly isolate problems in individual sections of the
system. If more than one element of the system is introduced at the same
time and there is a problem, it may take some time to isolate where the
problem is occurring.

This staggered introduction is commonly referred to as a "cutover". This
is because the two systems cut over one another as each element is
introduced. This is by far the most preferred method of introducing a new
computer system however there are times when it is not possible to do this.
Where the ability to introduce the system in sections is not available, -
for example, the new system is not compatible with the existing equipment,
which will be disposed of when the new system in commissioned - a different
implementation method must be used. Most commonly, it will be one that
involves the use of parallel systems.

As the name suggests, parallel system implementation is where two systems
(the current and the new ones) are being run at the same time to perform
the same job. While this duplicates the work, there are some significant
advantages to this type of system. As the performance of the existing
system is a known quantity, it gives us something to compare the
performance and accuracy of the new system to. Often parallel systems will
operate for a month or two before the old system is decommissioned. The
biggest problem with parallel systems is that the duplication of the work
can be costly however this must be viewed against the security of the
knowledge that if the new system under performs, the old system can be kept
operating until such time as all problems with the new system are sorted
out.

Where the new system requires the old hardware and/or software to be
removed, and it is not possible to have a cutover program or parallel
systems, the only option available is the use of a trial system. This is
where a small version of the system is set up and tried before the
widespread introduction of the system. This trial emulates all aspects of
the computer system to ensure that it will work properly. It aims to
reproduce as closely as possible the "real life" situation the system will
be used in. If the system is to be used in a number of locations, often
this trial will occur in a single location which crosses over to the new
system and evaluates its performance until it is satisfactory, at which
time it is then introduced to the rest of the company.

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