Explained: RAS on z/OS

A memory chip fails inside a running mainframe. In a typical server, this would be a crash: a blue screen, a kernel panic, an outage. On an IBM Z system, the error is detected, the affected memory is reconstructed from redundant data held elsewhere in the memory subsystem, and the repair is logged. The running workload continues without interruption. No operator is notified. No ticket is opened. The system fixed itself. This is not exceptional be… Read More

Architecture: Mainframe

Your bank's ATM runs 24 hours a day. The transaction you just made at the counter was confirmed in under a second. The insurance claim filed this morning will be processed overnight alongside three million others. None of that happens on a Kubernetes cluster. It happens on a mainframe. For engineers who grew up on distributed systems, the mainframe is a foreign country. The vocabulary is different. The mental model is different. Even the pric… Read More