A prescriptive planning approach for migration
sequencing in your large-scale public cloud
migration project.
When an enterprise has a large portfolio of applications slated for migration to
the public cloud, there is a need to identify the sequencing and scheduling
aspects of the migration.
In this article, we will describe a real-world planning exercise we undertook,
highlighting the various elements essential to any planning and sequencing
operation.
The following framework was used for migration sequencing:
• Develop a rules and scoring system that assigns a score to an application
based on preferences, such as less complex applications should migrate
first, and dependent groups of applications must be migrated together.
• Determine the scale and velocity of the migrations, including how many
applications can be migrated in a given time period.
• Create a schedule with preferences for what days migration can and
cannot be done – such as, no migrations can be performed on holidays.
• Create a backlog and iteratively apply any schedule preferences to select
applications for migration -- similar to a development project where
work from a backlog is added in a sprint for development.
Rules and Scores
Suppose we have 100 applications to migrate in a given time frame. To objec-
tively assess so many applications, we use a set of rules to score various appli-
cation components. Each rule has a base score for a specific characteristic of
an application component, and then additional points are added to indicate
various aspects of the characteristic - risk, complexity, effort, etc. Rules can
use weights to influence preferences when base scores are similar.
All scores are added up and the final scores indicate the order of migration. The
lower the score, the easier the application is to migrate (meaning less complex-
ity, less risk and lower effort required), and the earlier it should be placed on
the schedule.
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