Logical grouping of EC2 instances inside a single AZ (can’t span multiple AZ’s)
EC2 instances inside a group are assured to be connected to each other using a low latency, high network throughput 10 GB/S intranet
Two types
Cluster: Make them close
Spread: Opposite of cluster. Spread as far as possible
Only high end EC2’s such as Memory optimized (M), Compute optimized (C), Storage Optimized(I), GPU Optimized (G)
Recommended to launch homogeneous (same size/family) EC2s inside a Placement Group
Moving a running EC2 into a PG is not supported. Only while launching, you can choose your PG
The data in an instance store persists only during the lifetime of its associated instance. If an instance reboots (intentionally or unintentionally), data in the instance store persists. However, data in the instance store is lost under the following circumstances: