# Placement groups and instance launch issues
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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`](Scheduling-v3.md#Scheduling-v3-SlurmQueues) / [`Networking`](Scheduling-v3.md#Scheduling-v3-SlurmQueues-Networking) / [`PlacementGroup`](Scheduling-v3.md#yaml-Scheduling-SlurmQueues-Networking-PlacementGroup) / [`Enabled`](Scheduling-v3.md#yaml-Scheduling-SlurmQueues-Networking-PlacementGroup-Enabled) parameter to `false`.

For additional control over capacity access, consider [launching instances with ODCR (On-Demand Capacity Reservations)](launch-instances-odcr-v3.md).

For more information, see [Troubleshooting instance launch issues](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/troubleshooting-launch.html) and [Placement groups roles and limitations](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html#concepts-placement-groups) in the *Amazon EC2 User Guide for Linux Instances*.