Blog

EC2 Placement Groups
This is how we can specify each instance physically be apart or stay closer to one another

Cluster Placement Group – Pack instances close together
Spread Placement Group – Keep instances separated
Partition Placement Group – Groups of instances spread apart

Cluster Placement Group:

• Can’t span AZs – One AZ only – locked when launching first instance
• Can span VPC peers – but impact performance
• Require a supported instance type
• Launch at the very same time (not mandatory but recommended)
• 10 Gbps single stream performance
• Performance, fast spee,d low latency
• Likely on same rack

Spread Placement Groups

• Provide infrastructure isolation
• each rack has its own network and power source
• 7 instances per AZ (HARD LIMIT)
• Not supported for dedicated instance or host
• Use case is usally for keeping small number of instances that needs to be separated from each other

Partition Placement Groups

• 7 Partitions per AZ
• Instance can be placed in a specific partition
• great for topology aware applications