burn in

Acceptance is a contract document, not a checklist, so every criterion has to be a number with a tolerance that a vendor can be held to. Comparing nodes against each other rather than against a datasheet is what finds real defects, and the duration is what finds the thermal ones.

Two failures and a pass is not a passing node, it is a node with a demonstrated intermittent fault and a small sample. The arithmetic that shows how weak the evidence for acceptance is, what an intermittent fault costs once it is in a training job, and the policy that removes the argument.

A pre-flight suite is a list of tests with a number on each: DCGM health, a GEMM near the fleet median, NCCL at rated bandwidth, NICs at line rate, links active, storage reachable. What goes in the two-minute gate, what waits for the long diagnostic, and why the gate pays for itself.

Infant mortality is real and diagnostics that run for a minute do not find it. The five-stage acceptance suite with what each stage catches and how long it takes, the pass criteria as numbers rather than judgments, and the sustained-load stage that finds the faults everything else misses.