【转自MOS文章】把RAC当HA用的数据库参数

最新推荐文章于 2021-04-05 01:08:57 发布

翻译最新推荐文章于 2021-04-05 01:08:57 发布 · 749 阅读

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本文详细解析了Oracle RAC环境中ACTIVE_INSTANCE_COUNT参数的作用及其配置方式。当该参数设置为1时，集群中首先启动的实例将成为主实例并接受客户端连接；第二个启动的实例作为备用实例，在主实例故障时接管服务。文章还介绍了当监听器关闭时可能遇到的Ora-12516错误。

以下来源于：

Ora-12520/12516 Received When Listener on Node 1 is Down in RAC Setup. (文档 ID 357882.1)

ACTIVE_INSTANCE_COUNT set to 1 and primary instance is still running at the time of the test.
You have shutdown only the Listener so it leads to Ora-12516.

ACTIVE_INSTANCE_COUNT enables you to designate one instance in a two-instance cluster as the
primary instance and the other instance as the secondary instance. This parameter has no
functionality in a cluster with more than two instances.

When you set this parameter to 1, the first instance you start up becomes the primary instance and
accepts client connections. The second instance starts up as a secondary instance and can accept
client connections only if the first instance fails. In such an event, the secondary instance
becomes the primary instance.

When the failed instance can once again be started up, it starts up as the secondary instance, and
will not accept client connections unless the current primary instance fails.