X100 cluster interconnect: DAC vs short-run optical

Question

Building out a 3-node X100 cluster, all racks adjacent. Datasheet says QSFP-DD ports handle both DAC and optical. Sales suggested DAC for cost and lower latency, but our facilities team prefers optical for hot-swap cleanliness. Anyone deployed both and have thermal / signal-integrity notes? Cluster interlink runs at 200 Gbps aggregate here.

Samir Al-Otaibi · Answer

3-node X100 cluster here, running QSFP-DD DAC interconnect for 6 months. Zero issues, zero re-seats. Thermal was fine — the DAC connectors don't add anything meaningful in our layout.

Min-Jun Park · Answer

We went optical purely for the cable management story (you can pull a fibre without disturbing anything else). If your facilities team has strong opinions, don't fight them — the perf delta is negligible at 200G aggregate.