Placement groups and instance launch issues

To get the lowest inter-node latency, use a placement group. A placement group ensures that your instances are on the same networking backbone. If there aren't enough instances available when a request is made, an InsufficientInstanceCapacity error is returned. To reduce the possibility of receiving this error when using cluster placement groups, set the SlurmQueues / Networking / PlacementGroup / Enabled parameter to false.

For additional control over capacity access, consider launching instances with ODCR (On-Demand Capacity Reservations).

For more information, see Troubleshooting instance launch issues and Placement groups roles and limitations in the Amazon EC2 User Guide for Linux Instances.