Placement Groups

• influence close or not
• three type

  1. cluster - pack instances close together

     • launch all instance within a groups in a AZ, cannot span AW
     • fast direct bandwidth with single stream transfer rate with lowest latency possible
     • same rack, same time, same host
     • can span VPC peers
     • better to use the same type of instance/ at the same time
     • use cases: performance, fast speeds, low latency

     Untitled.png

  2. spread - keep instances separated

     • spread across the AZ with distinct rack
     • provides infrastructure isolation, each instance runs from a different racks
     • each eack has its own network and power source
     • limit: 7 instances per AZ
     • use case: small number of critical instance that need to be kept separated from each other (eg domain controller/ file system)

     Untitled 1.png

  3. partition - groups of instances spread apart

     • spread across the AZ with distinct rack
     • maximum of 7 partitions per AZ
     • in each partition you launch multiple instance
     • huge scale parallel computation but will have the resilience
     • great for topology aware application

     Untitled 2.png