Despite some pundits' beliefs, organizations in finance, banking and insurance still use mainframes, though lack of staffing expertise makes it tougher to maintain and run mainframes.
If your organization doesn't have staff with mainframe knowledge or can't recruit new staff to run these systems, your team may consider that it is time to retire the infrastructure.
For successful mainframe decommissioning, your team must consider what data to keep within the organization, if they should replace any supported software and hardware disposal costs.
Start with application inventory
The first step in any mainframe retirement project is to create a comprehensive inventory of the applications the mainframe currently hosts. Once you identify all of the supported applications, then you must determine which programs you still need and which ones to remove.
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There are typically going to be at least a few applications that are no longer needed, and the mainframe retirement process is easier if you decommission those applications before you move forward.
Once you decide which applications to retire or keep, you must answer two important questions for each application: How to continue operating the application in the mainframe's absence and how to prevent service disruption during the transition period.
Outsource mainframe operations
One option for running your mainframe applications after decommissioning is to outsource your mainframe operations to a provider that specializes in mainframes.
The advantage to outsourcing mainframe operations is that it is potentially the least complicated option. Doing so allows you to still run your mainframe applications on a mainframe without the need for in-house expertise or maintenance.
The disadvantage to mainframe outsourcing is that it can be tough to find a nearby service provider who specializes in mainframes and outsourcing could be costly.
Replatform programs to run on x86 hardware
Another option is to replatform your mainframe applications so that they can run on x86 hardware. Replatforming existing applications after mainframe decommissioning tends to be a low-risk and relatively low-cost option as long as you do not introduce application code changes during the replatforming process.
Once you replatform an application, you can run it on x86 hardware in your own data center or in the cloud. Regardless of where you host the application, you must consider the x86 hardware's ability to deliver the same level of application performance as when the mainframe hosted the software. Your choice of hosting technology also depends on how frequently you must access the data.
You should also think about what to do with the application data. Migrating petabytes of data to the cloud may prove to be logistically impractical, or cost-prohibitive, but might be the best option in certain use cases.
There are other data-related considerations beyond storage capacity. You must also consider which storage architecture will provide the application's required level of storage IOPS without introducing excessive latency.
New application adoption
Though most mainframe decommissioning projects focus squarely on application migration, simply moving the application isn't always the right choice. It sometimes makes more sense to adopt a new application.
Whether you build the application in-house or opt for a commercial offering, aging application replacement can help the organization better use existing data. A new application can offer an improved workflow that streamlines business processes. An updated software might also provide a better user experience or even increase how users can access the data.
There are three potential disadvantages to replacing an aging application with a new software. First, application replacement can increase your licensing costs, because more vendors are replacing perpetual license models for as-a-service setups.
Second, introducing a new application is disruptive. You must prepare to deal with a learning curve for both the users and your team.
Third, there is a chance that a new application lacks a specific feature that the users depend on to do their jobs, or there isn't a suitable application replacement available.
Security and hardware removal
Even though application planning is arguably the most important part of the mainframe decommissioning process, there are also security concerns. You must come up with a plan to ensure that your data is secure after you bring the mainframe offline. You may need to delete the mainframe's contents, degauss the mainframe's storage or physically destroy any hard drives.
Once all the data and applications are migrated, you must dispose of the mainframe hardware. Whether your organization decides to sell or to recycle the old mainframe, you must have a moving plan.
Though physical specifications vary among makes and models, mainframes are large and heavy. For example, the IBM ZR1 weighs over 800 pounds. This means that you must coordinate any hardware removal with a professional provider that can efficiently remove all hardware and properly dispose of the mainframe.