Selecting Cluster Type

There are three types of EMR clusters, and you can choose one as needed:

• Hadoop cluster: it provides open-source big data components such as Hadoop, HBase, Hive, Spark, Flink, and Presto and is mainly used in big data processing scenarios such as offline, real-time, and ad hoc data analysis.
• ClickHouse cluster: it provides the open-source column-oriented database component ClickHouse and is mainly used in analysis of events or log streams that have a clear and fixed structure.
• Druid cluster: it provides the distributed time-series database component Druid and is mainly used in queries of massive amounts of aggregated data based on time series.

Selecting Billing Mode

Billing mode provided by EMR cluster:

• Pay-as-you-go cluster: the billing mode of all nodes in a cluster is pay-as-you-go. It is suitable for clusters that exist for only a short period of time or periodically.

For more information on node types, please see Node Type Description.

Selecting Model Specification

EMR offers a wide variety of CVM instance models, including EMR Standard, EMR Compute, EMR High IO, EMR MEM-Optimized, and EMR Big Data (if you need CPM models, please contact us by submitting a ticket).

• The minimum number of nodes in a high-availability (HA) Hadoop or Druid cluster is 8, including 2 master nodes, 3 common nodes, and at least 3 core nodes. A non-HA cluster adopts single-replica storage, which can be used for testing but is not recommended for use in production environments, and its minimum number of nodes is 3, including 1 master node and at least 2 core nodes.
• The minimum number of nodes in a high-availability (HA) ClickHouse cluster is 5, including 2 core nodes and 3 common nodes. A non-HA cluster adopts single-replica storage, which can be used for testing but is not recommended for use in production environments, and it should contain at least 1 core node.

You can choose the most appropriate model based on your business needs and budget.

• If you require low latency for offline computation, you are recommended to choose the model with a local disk or the Big Data model.
• If you need to use the real-time database HBase, you are recommended to choose the EMR High IO model with a local SSD disk for optimal performance.

Node specification recommendation

Network and Security

To ensure the network security of the EMR cluster, it is placed in a VPC, and a security group policy is added to the VPC. In addition, to ensure that the web UI of Hadoop can be easily accessed, one of the master nodes is configured with a public IP which is billed by traffic. A router node has no public IPs by default. If you need one for it, you can bind it to an EIP in the CVM Console.

• A public IP is enabled for a master node when a cluster is created, but you can disable it based on the actual conditions.

• Enabling the public IP for the master node is mainly for SSH login and component viewing in the web UI.
• A master node with a public IP enabled is billed by traffic with a bandwidth of up to 5 Mbps. Once the cluster is created, you can make adjustments to its network in the console.