AWS > Compute > Amazon Elastic Compute Cloud (EC2):
When you launch a new EC2 instance, the EC2 service attempts to place the instance in such a way that all of your instances are spread out across underlying hardware to minimize correlated failures.
Three types of Placement Groups:
1. Cluster Placement Groups
2. Spread Placement Groups
3. Partition Placement Groups
Placement Group General Rules and Limitations:
1. The name you specify for a placement group must be unique within your AWS account for the Region.
2. You can't merge placement groups.
3. An instance can be launched in one placement group at a time; it cannot span multiple placement groups.
Cluster Placement Groups:
A cluster placement group is a logical grouping of instances within a single Availability Zone. A placement group can span peered VPCs in the same Region.
Cluster placement groups are recommended for applications that benefit from low network latency, high network throughput, or both, and if the majority of the network traffic is between the instances in the group.
Spread Placement Groups:
A spread placement group is a group of instances that are each placed on distinct racks, with each rack having its own network and power source.
Spread placement groups are recommended for applications that have a small number of critical instances that should be kept separate from each other. Launching instances in a spread placement group reduces the risk of simultaneous failures that might occur when instances share the same racks.
A spread placement group can span multiple Availability Zones in the same Region. You can have a maximum of seven running instances per Availability Zone per group.
Partition Placement Groups:
When using partition placement groups, Amazon EC2 divides each group into logical segments called partitions. Amazon EC2 ensures that each partition within a placement group has its own set of racks. Each rack has its own network and power source. No two partitions within a placement group share the same racks, allowing you to isolate the impact of hardware failure within your application.
Partition placement groups can be used to deploy large distributed and replicated workloads, such as HDFS, HBase, and Cassandra, across distinct racks.
A partition placement group can have partitions in multiple Availability Zones in the same Region. A partition placement group can have a maximum of seven partitions per Availability Zone.
Reference:
1. AWS Documentation - Placement Groups:
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html
2. Udemy - AWS Solutions Architect - Associate:
https://www.udemy.com/aws-certified-solutions-architect-associate/
最初發表 / 最後更新: 2020.01.08 / 2020.01.08
0 comments:
張貼留言