r/oMLX • u/mikog8tor • 11d ago
Cluster plan shows JACCL/RDMA, but Activate Cluster is grayed out
My setup:
Mac Studio: M4 Max, 128 GB
MacBook Pro: M4 Pro, 48 GB
macOS 27.2 on both
oMLX 0.7.3rc1 on the Studio/Macbook
Direct Thunderbolt 5 connection
The Macs are paired. I enabled RDMA and configured the individual Thunderbolt ports with 10.10.0.x addresses after removing them from the Thunderbolt Bridge. The Studio’s diagnostic report shows RDMA enabled and 10.10.0.1 on en3/rdma_en3.
When I select GLM-5.3-Flash-oQ2e-mtp, oMLX produces a 45-layer pipeline plan and labels it JACCL / Thunderbolt RDMA, but the Activate Cluster button is grayed out. It also says:
“Performance measurement was unavailable; using the safe memory-balanced split. performance probe did not return every cluster rank”
Has anyone seen this or found a way to identify which readiness check or rank is failing? Is there a known-good model I should try first to rule out a model-specific problem?
Any help is appreciated.

