What even is a mainframe? I’ve been involved in software and infrastructure for 20+ years, I understand data centres, servers, services, microservices, databases, HA/SPOF, clusters and all the cloud equivalents, but never came across a mainframe. It’s almost a legend – are mainframes a real thing? What do/did they do? What’s happening to them? Where are they?
In: Engineering
Mainframes are a very specific type of machine, from a somewhat different time. Before the modern status quo of using a swarm of (comparatively) small servers, we had the era of one massive, individual server. And I do mean massive. IBM’s current [z16 mainframes](https://www.ibm.com/products/z16) can take up to 40TB of RAM.
Given you’re aware of the issues with single points of failure and high availability, it should be fairly obvious that having just one single server with everything on it is dangerous as hell, you’re one bad crash away from losing everything. Mainframes are designed around mitigating that problem: everything is redundant and hot swappable. Never mind hot-swapping discs the way you do now, or even RAM. On these things you can easily drain all load from one CPU to another so you can replace the CPU while the whole machine is still running.
Latest Answers