The Multi-Core Reality: When Replacing the Mainframe Isn't the Answer

Freedom inside a large bank is not the absence of constraint. Daniele Tonella, CTO and Member of the Management Board at ING, defines it as digital sustainability — holding a balance between reducing complexity and creating room for the new. Lose that balance, reach the point where there is nothing left to spend on cleaning up, and the institution is simply carried along by its own economics.

Trust has to be engineered as deliberately as anything else. Joe Wilson, Chief Evangelist at bunq, describes Safety Shield, which holds unusual payments for twenty-four hours so a customer has time to reconsider — a direct response to fraud that increasingly targets the user rather than the system. AI is a considerable time saver, he notes, and equally an arms race in which both sides are armed.

Architecturally, the honest starting point is that the core is the core. Cornel Dixon, Head of Growth at Plumery, explains why: robust, often slow, and necessarily stable, because it holds every customer record. Trouble starts when the experience is bolted straight onto it. The alternative he sets out is a multi-core approach, leaving the mainframe where it is and introducing something leaner alongside it, and he is specific about where that makes sense and where it does not.