Not COBOL itself, but Mainframes/Z systems are known for their high availability/reliability. Mainframes have many hardware redundancies that help contribute to

Not COBOL itself, but Mainframes/Z systems are known for their high availability/reliability. Mainframes have many hardware redundancies that help contribute to their fantastic uptimes, despite being a single unit. One might ask why a distributed system wouldn’t be better, which is a fair question. It really depends on what you are doing. This is where the CAP theorem comes into play. For situations where data consistency is a must, mainframes are a good fit. If you look at some of the notable examples of where mainframes are used, such as VISA transactions or banking, you'll see that data consistency is critical in these situations. Building a comparable distributed system would not be an easy feat. Mainframes, especially modern ones, are pretty cool imo. The obvious downside is the high cost, which makes them very unappealing for startups. There was a thread last week asking why cloud hasn't killed the mainframe, which I thought had some pretty good replies: https://news.ycombinator.com/item?id=37333837 https://news.ycombinator.com/item?id=37333837