Information Technology Reference
In-Depth Information
task
concept
preparation
implementation
starting position
data base
sequencing
system
dump
fall-back scenario
functional tests
clean up
operation
Fig. 6.2
Migration systematics
For each migration module the responsibilities for communication and partici-
pating systems have to be defined. Mutual understanding of responsibilities is
important—just as with any acceptance process in general. Again in this case as
well everything should be arranged early on in a dedicated kick-off. During the
kick-off the “internal sponsor” should be identified. Contrary to the clear terms
accompanying the delivery of a release by an external supplier the initiative for
migration comes from within the company itself. It is quite often addressed to a
service provider residing in the same company. These relationships and responsi-
bilities have to be worked out explicitly—best by service level agreements.
Another important part of the functional specifications is a check list which not
only documents the time sequence of the migration steps but also all preparation
measures making the process possible in the first place.
Contrary to pure functions the content to be accepted has to be defined separately.
This touches upon questions concerning data consistency, tolerances and data volume
including quality and quantity. An appropriate data controlling has to be set up.
6.3 Planning and Implementation
A careful preparation will later save cost intensive repetitions and data clean-up
measures. The target system has to deal with twice the data volume. It has to be
decided whether a test run on a separate test system using a representative selection
of data should be executed to begin with (to be recommended!). Prior to migration a
dump of the exiting data base has to be done to be able to reconstitute the previous
state under controlled conditions.
