A cluster placement group packs EC2 instances close together within a single Availability Zone, providing low latency and high network throughput (up to 10 Gbps or more) ideal for tightly coupled, high-performance computing workloads.

A cluster placement group places EC2 instances into a single Availability Zone, packing them close together on the same high-bandwidth, low-latency network fabric. This configuration enables instances to achieve non-blocking 10 Gbps network performance (up to 100 Gbps on compatible instance types) and single-digit millisecond latency. Cluster groups are ideal for tightly coupled, latency-sensitive workloads where inter-instance communication is critical, such as high-performance computing (HPC), financial simulations, and large-scale machine learning training.

Create and Use a Cluster Placement Group

Cluster Placement Group Requirements

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All instances must be in the same Availability Zone
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Use instance types that support enhanced networking and placement group awareness (e.g., C5n, M5n, R5n, P3dn)
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Recommended to launch all instances in the same request or use launch templates for consistent placement
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Maximum of 20 instances per placement group, though you can request a higher limit by contacting AWS Support
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Use Elastic Fabric Adapter (EFA) for even lower latency and higher throughput on compatible instances

Best Use Cases

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High-performance computing (HPC) clusters
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Large-scale simulations (computational fluid dynamics, weather modeling)
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Financial risk modeling and real-time trading analytics
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Machine learning distributed training (e.g., TensorFlow, PyTorch with Horovod)
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Real-time data processing with low-latency requirements
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Network-bound applications requiring non-blocking 10 Gbps+ throughput