Comparison
TaintvsToleration
Taint
the expensive GPU nodes sat empty because they push away every workload that has not explicitly said it can live there.
A mark on a node that repels workloads unless they carry a matching exception. It is the node's own defence — the node decides what it will not take — and it is how you keep general workloads off special hardware, off control-plane machines and off nodes being drained. The direction is the thing to hold on to: a taint pushes away, and only a toleration lets something through.
Full entry →Toleration
the workload carries a note saying it can live with the thing that node is marked with, so the scheduler stops excluding it.
A workload's declaration that a particular taint does not disqualify it. It permits placement, it does not request it: a workload with a toleration for GPU nodes will happily be scheduled onto ordinary ones instead. That is the pairing people get wrong — tolerations plus node affinity is what actually pins something to special hardware, and a toleration alone does nothing of the kind.
Full entry →