Oracle 参数 ACTIVE_INSTANCE_COUNT 官方解释，作用，如何配置最优化建议
本站中文解释
ACTIVE_INSTANCE_COUNT是Oracle的一个性能参数，它控制着可以同时运行的内存实例的数量。设置此参数的目的是避免内存多次被访问而同时又不耗尽内存，从而提高系统性能。
正确设置ACTIVE_INSTANCE_COUNT参数要根据每台物理服务器的实际配置来进行，具体步骤如下：
1. 计算服务器物理内存总大小；
2. 使用服务器管理软件，仔细计算出可供Oracle使用的实际内存；
3. 根据服务器可供Oracle使用的实际内存大小来计算需要设置的ACTIVE_INSTANCE_COUNT参数值；
4. 根据参数计算结果，在Oracle中设置ACTIVE_INSTANCE_COUNT参数。
官方英文解释
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.
| Property | Description |
|---|---|
|
Parameter type |
Integer |
|
Default value |
There is no default value. |
|
Modifiable |
No |
|
Modifiable in a PDB |
No |
|
Range of values |
1 or >= the number of instances in the cluster. (Values other than 1 have no effect on the active or standby status of any instances.) |
|
Basic |
No |
|
Oracle RAC |
You must set this parameter for every instance, and multiple instances must have the same value. |
Note:
The ACTIVE_INSTANCE_COUNT parameter is deprecated. It is retained for backward compatibility only.
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.
Note:
This parameter functions only in a cluster with only two instances.
