[CentOS] two 2-node clusters or one 4-node cluster?

Fri Jul 6 16:27:19 UTC 2018
Warren Young <warren at etr-usa.com>

On Jul 5, 2018, at 1:07 PM, Alexander Dalloz <ad+lists at uni-x.org> wrote:
> classical cluster setups are so 2000s. Outdated by modern infrastructure concepts you see implemented in Kubernetes, OpenShift or cloud solutions in general. It's commonly summarized in the phrase "pets versus cattle". You don't want clusters to be treated as pets.

That depends on how expensive it is to grow the herd, to extend your metaphor.

For example, if you have a big DBMS, it’s probably much, much faster to maintain a live spare that you can fail over to instantly than it is to spin up a new VM with OpenKuberStack® and clone the complete DBMS over the Internet.  At 1 Gbit/sec, every 10 TB costs you about a day of replication time!

The herd-of-cattle model and follow-ons like “serverless” assume you can spin a new one up in a second or so.  That ain’t always possible.