Consider your constraints

Most legacy modernization projects for moving to Azure have constraints, meaning there are non-technical constraints, such as time and money, or technical, meaning things such as scalability and performance that have to be addressed. This section will cover these constraints.

Time constraints

Many legacy migrations are bounded by time constraints. With mainframes, this is the process of renewing the mainframe hardware, which typically happens every 3 years. This can help define the time frame necessary for the migration to be completed. It is very important to understand the size of the workloads and the number of lines of code that need to be migrated to meet this time frame. There are various types of time constraints, depending on the industry you are in:

• Hardware renewal constraints: As mentioned earlier, these are for support and maintenance and are typically 3 to 5 years.
• Hardware supportability constraints: For most hardware vendors, they only support previous versions of the hardware back to a certain version. They vary by vendor.

Resource constraints

Even though there are large parts of a migration that can be automated, another bounding factor is the number of resources necessary for the migration. This is extremely important when it comes to testing, both smoke testing and user acceptance testing. Human resources such as developers and testers are critical, as are resources such as testing and development environments.

Funding constraints

And we cannot forget about funding the migration. There are multiple costs to consider that need to be aligned with the funding to make sure the migration is even worth the effort. Perhaps buying and implementing a COTS or Software as a Service (SaaS) solution would be more efficient:

• The cost of the Azure infrastructure: This cost is relatively easy to calculate. It involves mapping the compute from the legacy system to Azure vCPUs, as well as the storage and networking to the appropriate Azure artifact.
• The third-party software costs: Depending on the migration software vendor, there will be additional software costs for additional components of the solution. A good example is if the legacy solution leverages a scheduler on the legacy platform; a corresponding scheduler will need to be implemented in Azure.
• The migration cost: Even though automation can be used to minimize the number of people necessary to migrate a solution, the actual migration, be it a rehost, refactor, or rewrite, will be a significant part of the cost of the migration.

Now that we’ve looked at constraints, we will look at defining success for a modernization project.