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There is no such thing as a zero downtime system, and it is a fiction that makes it difficult to have real conversations about trade offs with a business. Movin
by cpitman 7y ago
There is no such thing as a zero downtime system, and it is a fiction that makes it difficult to have real conversations about trade offs with a business. Moving towards zero downtime requires rapidly escalating cost to incrementally move the needle.
At a minimum, supporting infrastructure (power/networking/internet/etc) will eventually fail even with backups. On top of that, no mainframe is going to work when under water (flooding) or on fire (remember the delta outage?).
- waterheater 7y agohttps://news.ycombinator.com/item?id=20977332 https://news.ycombinator.com/item?id=20977332 > The last time he did shutdown the Mainframe was 15 years ago And that was a controlled shutdown, not uncontrolled. If more than fifteen years is your time horizon to validate the zero downtime claim, that's cool. By that point, though, the system will have proven its worth. Right; unreliable supporting infrastructure is the inherent trickiness with saying the mainframe has zero downtime. The manufacturer isn't being deceptive, though, if, given reliable supporting infrastructure, the system will stay online for as long as is stated. It's just not their problem. Can't imagine a company would blame a manufacturer for downtime in the event of a flood/earthquake to protect the equipment. If a piece of equipment starts on fire, that's another story, but I suppose a zero-downtime system makes assumptions that it won't start on fire.
- cat199 7y agoAgree from theoretical perspective you are correct - however, with a good implementation of a real-time multisite replication you can just about eliminate the variable.. https://en.wikipedia.org/wiki/IBM_Parallel_Sysplex https://en.wikipedia.org/wiki/IBM_Parallel_Sysplex