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3 posts tagged
infiniband. All tags →
The subnet manager picks the routing engine, and the routing engine decides whether your fabric deadlocks. Min-hop, Up/Down, fat-tree and DragonFly+, and what each one is actually protecting you from.
ibdiagnet is the first command to run on a sick fabric. What its output files contain, which counters actually matter, and how to get from a slow training job to a specific port.
When a fabric link flaps or runs at the wrong width, the answer is usually in the optics. How to read PCIe and fabric port state, per-lane signal quality and cable EEPROM with the NVIDIA firmware tools.