Not much detail but Santander post has more details https://www.santander.com/en/press-room/press-releases/2022/10/google-and-santander-to-help-other-companies-

Not much detail but Santander post has more details https://www.santander.com/en/press-room/press-releases/2022/10/google-and-santander-to-help-other-companies-simplify-their-transition-from-legacy-tech-to-the-cloud https://www.santander.com/en/press-room/press-releases/2022/... > To enable the transformation and modernization of its core banking, the bank is using Gravity, a bespoke internal software which has been developed in-house and allows parallel processing, meaning the bank can simultaneously run workloads on its existing mainframe and on the cloud, allowing it to perform real-time testing with no disruption to its businesses. My guess is that this software captures CICS transactions, sends them to "the cloud", and then validates if both system provide the same results. I have no idea how they synchronize BATCHs input/outputs but given the goal to drop "mainframe" they probably already migrated the database to a cloud hosted one so when a BATCH is updating data is already updating CLOUD data.