“Pulling the plug” on obsolete legacy systems is the least talked about and most likely least understood of legacy modernization options. In our modern world of green economics and recycled resources, we often feel guilty for simply discarding a productive asset that duly served our business for many years. Contrary to all other legacy modernization approaches, this wasteful action makes no attempt to leverage any part of the residual value that can be found in the disposed system. This is a terminal event filled with so much negative connotation that we even had to create a special euphemism to deal with it—application sunsetting.
Here Today, Gone Tomorrow?
What can be simpler than removing obsolete systems from your application portfolio? Practical experience shows that considerable amounts of preparation and analysis are required before successfully executing this seemingly trivial task. Every so often, we watch on local TV news a broadcast of demolition events for a local landmark—an old stadium or an antiquated bridge. Wrapped in nostalgia and a cloud of dust, these dignified, aging structures collapse to make way for new, modern creations. Just think of all the skills and the required planning that went into these demolition events. The demolition of old IT systems carries its own set of complexities along three dimensions: source code archiving, data archiving, and inter-system dependencies and interfaces.
Source Code Archiving: Why?
In the real world, taking a full inventory and archiving a complete library of source codes for the discontinued system is a prudent action. It’s very possible that with the passage of time you may want to go back to this source code to get better insight into its old business rules and calculation algorithms. It may turn out that the newly deployed replacement system is negatively impacting your business in the most unexpected ways and the clues to your past successes are locked deep inside the old source codes. As an additional consideration, our litigation-driven society is always full of surprises as to when the moment may come to defend your past business practices against unwarranted claims. All in all, preserving full copies of decommissioned source codes is a good defensive move for both knowledge preservation and regulatory/litigation considerations.
Data Archiving: Government Mandate
Not only is preserving legacy data equally important to preserving legacy code but it’s most likely legislatively mandated in your industry. Many government mandates, such as SOX and HIPAA, are focused on preserving and protecting historical data. Even if your business no longer has a need for retired application data, it’s most certain that an existing government regulation and, yes, once again, prospects of future potential litigations necessitate much longer preservation of such data.
Data archiving is much more complex than source code archiving. Data archiving complexities stem from the sheer volume of data that needs to be retained as well as availability of the underlying database engines required to access this data. Imagine the need to preserve terabytes upon terabytes of old data for a mandated retention period of more than 50 years. Now imagine that the need arises to access this data 20 years from now using IDMS database manager—the original source of this data. What are the chances you will still have an active license for IDMS database manager in 2030? What are the chances you will still be running a mainframe with an operating system capable of hosting this IDMS database manager in 2030?
The Inter-System Dependencies Challenge
N o IT system is an island. Intricate and complex system interfaces and data dependencies weave a tangled web that binds application portfolios on multiple levels. Precision and skill equal to that of a neurosurgeon are sometimes required to painlessly remove an obsolete system from such interconnected application portfolios. Deep system analyses facilitated by graphic legacy understanding tools and careful attention to details are key to this activity. Furthermore, most likely a new set of interfaces and data bridges will need to be developed to compensate for removal of the retired systems.
Farewell to Old Friends
Putting things into perspective, application sunsetting is a complex task that requires proper planning and significant skill. To give these legacy systems their due for all the years of serving our business, we can only hope they will be remembered with the same fondness and respect as the images of the old Hollywood heroes riding into the nostalgic sunset. ME