Infographic 09 · D3 · Aliens block
The queen does not hunt. She keeps a count, notices when it is wrong, and acts. Kill a node and the loop behaves exactly as it would if the power had failed, which is the claim worth taking away.
Move the replica dial past twelve and the loop cannot close the gap at all. It keeps trying anyway, because there is no state in which it decides the gap is acceptable.
| Step | What it is |
|---|---|
| Desired | six replicas, written down in a file |
| Observed | what is actually running, right now |
| Gap | the only input the loop reads |
| Act | schedule the difference, anywhere with room |
| Node | Capacity |
|---|---|
node-a | 4 slots |
node-b | 4 slots |
node-c | 4 slots |
The failure this figure does not draw is the interesting one. A container that dies during startup, every time, produces the same gap forever, and the loop restarts it all night. That is a working scheduler and a completely dead service at once.
Campaign day 80. The written piece is in the writing index.