Amazonrds 简明教程

Amazon RDS - Multi-AZ Deployments

在多可用区部署中，Amazon RDS 会自动配置并维护其他可用区的同步待机副本。主 DB 实例会跨可用区同步复制到待机副本，以提供数据冗余、消除 I/O 冻结，并在系统备份期间最大程度地减少延迟峰值。使用具有高可用性的数据库实例可以在计划的系统维护期间提高可用性，并有助于在数据库实例发生故障和可用区中断时保护数据库。

In a Multi-AZ deployment, Amazon RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone. The primary DB instance is synchronously replicated across Availability Zones to a standby replica to provide data redundancy, eliminate I/O freezes, and minimize latency spikes during system backups. Running a DB instance with high availability can enhance availability during planned system maintenance and help protect your databases against DB instance failure and Availability Zone disruption.

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Creating Multi-AZ deployment

你可以在创建数据库实例时选择多可用区部署选项，也可以选择将现有数据库实例修改为多可用区数据库实例。下图显示了修改现有选项的选项。但在创建数据库实例时，也可以找到相同的选项。

You can choose the option of selecting a multi-AZ deployment when creating a DB instance or you can also choose the option of modifying an existing db instance to become a multi-AZ DB instance. The following diagram shows the option where we are modifying an existing option. But the same option is also available during the creation of the DB instance.

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How Multi-AZ works

如果你的数据库实例发生计划内或计划外的中断，并且你已经启用了多可用区，Amazon RDS 会自动切换到另一个可用区的待机副本。故障转移完成所需的时间取决于数据库活动和主数据库实例变得不可用时的其他条件。故障转移时间通常为 60-120 秒。然而，大型交易或冗长的恢复过程可能会增加故障转移时间。

In the event of a planned or unplanned outage of your DB instance, Amazon RDS automatically switches to a standby replica in another Availability Zone if you have enabled Multi-AZ. The time it takes for the failover to complete depends on the database activity and other conditions at the time the primary DB instance became unavailable. Failover times are typically 60-120 seconds. However, large transactions or a lengthy recovery process can increase failover time.

对于 Oracle、PostgreSQL、MySQL 和 MariaDB DB 实例的多可用区部署使用 Amazon 的故障转移技术。SQL Server DB 实例使用 SQL Server 镜像。

Multi-AZ deployments for Oracle, PostgreSQL, MySQL, and MariaDB DB instances use Amazon’s failover technology. SQL Server DB instances use SQL Server Mirroring.