问题描述

当我恢复 MySQL 快照时，我可以选择将新实例设为多可用区.但是由于某种原因，当我恢复到 Aurora 时，多可用区部署"选项被禁用.

When I restore a MySQL snapshot, I'm given the option to make the new instance Multi-AZ. However for some reason when I restore to Aurora, the "Multi-AZ Deployment" selection is disabled.

我认为这可能意味着它已自动启用.但是，当我转到正在运行的实例详细信息时，它特别列出了多可用区:否".

I thought possibly this meant it was automatically enabled. However when I go to the running instance details, it specifically lists Multi-AZ: "No".

有什么我遗漏的吗?制作 Aurora Multi-AZ 还需要执行其他步骤吗?

Is there something I'm missing? Is there some other step I need to do to make Aurora Multi-AZ?

推荐答案

多可用区在 Aurora 中的含义与在 MySQL 和 MariaDB 中的含义不同.使用 Aurora，集群中的任何副本都可以在故障时接替主节点(虽然选择是基于优先级的，所以它不仅仅是随机选择的副本，如果有多个副本)，并且存储已经是/always 在 Aurora 中使用多可用区，因为这是 Aurora 设计的核心部分.因此，Aurora 可以转换"为多可用区.

Multi-AZ doesn't mean the same thing in Aurora as it does for MySQL and MariaDB. With Aurora, any replica in the cluster can take over for the master on failure (though the selection is based on priority, so it isn't just a randomly selected replica, if there is more than one replica), and the storage is already/always multi-AZ in Aurora because that's a core part of the Aurora design. So, Aurora can be "converted" to Multi-AZ.

显然，这是从快照创建 Aurora 实例时的唯一方法，基于此:

Apparently, that's the only way it is done when creating an Aurora instance from a snapshot, based on this:

您可以迁移 Amazon RDS MySQL 数据库实例的数据库快照来创建 Aurora 数据库集群.

You can migrate a DB snapshot of an Amazon RDS MySQL DB instance to create an Aurora DB cluster.

...

您可以迁移手动或自动数据库快照.创建数据库集群后，您可以创建可选的 Aurora 副本.

You can migrate either a manual or automated DB snapshot. After the DB cluster is created, you can then create optional Aurora Replicas.

http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Aurora.Migrate.RDSMySQL.html

如果您创建一个没有快照的多可用区 Aurora 集群，这就是全部 - 创建一个主节点和一个副本.在这种情况下，您实际上可以删除副本并使其成为非多可用区，这与 MySQL 或 MariaDB 所涉及的过程不同.

If you create a multi-AZ Aurora cluster without a snapshot, that's all that happens -- a master and a replica are created. In that case, you can actually delete the replica and make it non-multi-AZ, which is a different process than what's involved with MySQL or MariaDB.

创建集群"——正如上面引用中所使用的——是一个可能令人困惑的术语，因为您自然会认为一个集群意味着两个或更多，但实际上 Aurora 集群在技术上可以是一个集群"只有一个实例.每个 Aurora 实例都是一个集群的一部分.一个实例是主(主)实例，任何其他实例都是副本.

"Create a cluster" -- as used in the quote, above -- is a potentially confusing term, since you would naturally assume a cluster means two or more, but in fact an Aurora cluster can technically be a "cluster" of just one instance. Every Aurora instance is part of exactly one cluster. One instance is the primary (master) and any additional instances are replicas.

如果数据库集群不包含任何 Aurora 副本，则会在发生故障事件期间重新创建主实例.

If the DB cluster doesn't contain any Aurora Replicas, then the primary instance is recreated during a failure event.

http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Aurora.Managing.html#Aurora.Managing.FaultTolerance

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