The computing layer of AnalyticDB for MySQL has good elasticity.
AnalyticDB for MySQL utilizes an architecture that separates storage resources from computing resources. Compute nodes can be decoupled from stateful storage nodes to become stateless. Scaling activities of compute nodes are no longer involved in migrating data in different states. Combined with extremely flexible capabilities at the Alibaba Cloud Infrastructure as a Service (IaaS) layer, the computing layer of AnalyticDB for MySQL can provide good scaling experience.
Typically, business has obvious peaks and troughs. During off-peak periods, resources are often idle. The time-specific scaling feature of AnalyticDB for MySQL allows you to customize scheduled elastic plans by day or by week. Scale-out is automatically performed before business peaks to handle business traffic. Scheduled elastic plans can meet the peak traffic requirements and reduces the costs of AnalyticDB for MySQL. For example, you can set zero node for a specific resource group during off-peak periods to minimize generated costs.
When the time-specific scaling feature causes changes in computing capabilities, the CPU processing capabilities and memory size of nodes of elastic I/O units (EIUs) must also be changed. AnalyticDB for MySQL manages processing capabilities by scaling up or down EIU nodes.
Each EIU node contains three replicas. Raft groups ensure the high reliability of and strong consistency among these replicas. You can use the following method to scale EIU nodes:
- Stop a replica. The Raft protocol keeps the majority of replicas online. Data reads and writes are not affected.
- Scale up or down the CPU and memory of the stopped replica based on elastic plans and then start the replica.
- Scale up or down the next replica until all replicas are scaled up or down.
- Perform the preceding operations on all EIU nodes.
The technical features of scaling up or down EIU nodes:
- EIU nodes are automatically scaled up or down based on time-specific elastic plans. Specifications are determined based on the computing capabilities specified in the plans.
- Business is not affected. The majority of replicas are online during scaling activities. Data reads and writes are not affected.