Architecture elements-High Availability

High Availability-foolproof

The main means to achieve high-availability architecture is data and serviceRedundancyBackup andTransfer failure.

Highly available applications:

The Application Layer mainly processes the business logic of website applications. Therefore, it is also called the business logic layer. An outstanding feature of an application is the stateless application. The so-called stateless Application means that the application server does not store the context information of the business, but only processes the corresponding business logic based on the data submitted by each request. Multiple service instances (servers) they are completely equal. requests are submitted to any server and the processing results are the same.

 

High-availability services:

L Hierarchical Management

L timeout settings

L asynchronous call

L service downgrade: two methods: Denial of Service (denial of non-critical services, or reduction of some non-critical services to ensure core services) and service closure.

L idempotence design: Some services must ensure that the results of repeated service calls are the same as those of one call.

 

High-availability data:

L CAP, in large websites, usually choose to enhance the availability (A) and scalability (p) of the distributed storage system, and to some extent discard consistency (c ). make some compensation and correction for inconsistent data.

 

Data Consistency can be divided into: strong data consistency; user data consistency; final data consistency.

L Data Backup

L failover