备用数据库上的数据可能根据客户端请求进行了修改。
The data on the standby database might be modified based on client requests.
给主和备用数据库的HADR配置参数设置适当的值。
Assign appropriate values to the HADR configuration parameters for both the primary and the standby database.
在备用数据库上生成的日志文件不能应用于源数据库。
The log files generated on the standby database cannot be applied on the source database.
而用户应用程序必须重新建立到这个被激活的备用数据库的连接。
The user applications will have to make new connections to this activated standby database.
在启动HADR时，如果主和备用数据库不相同，就会发生错误。
If the primary and standby databases are not identical when HADR is started, an error will occur.
在应用程序重新尝试连接之后，它应获得一个到备用数据库的新连接。
Once the application retries, it should obtain a new connection to the standby database.
为了使用分割镜像作为备用数据库，必须在目标系统上执行以下步骤。
Here are the steps required on the target system to use a split mirror as a standby database.
决定主和备用数据库服务器的主机名、主机ip地址和服务名或端口号。
Determine the host name, host IP address, and the service name or port number for both the primary and the standby database server.
这个HADR设置的主数据库名和备用数据库名是jsbmain。
The primary and standby database name for the HADR setup is jsbmain.
执行前滚恢复操作的结果与使用HADR在备用数据库上重播日志的结果略有不同。
The results of performing a roll-forward recovery operation could differ slightly from replaying the logs on the standby database using HADR.
一旦数据库处于一致状态，用户就可以切换到备用数据库，以便继续他们的工作。
Once the database is in a consistent state, users can switch over to the standby database to continue their work.
您需要等待备用数据库连接到主要数据库之后，才能使两个数据库处于对等模式。
You will need to wait until the standby database makes a connection with the primary database to get both databases in peer mode.
连接备用数据库，执行STARTHADR命令在备用服务器上启动HADR。
Connect to the standby database and start HADR on the standby server by executing the start HADR command.
如果主站点发生全站点事故，远程备用数据库会接替主数据库，从而保持数据可用性。
If a complete site failure occurs at the primary site, data availability is maintained by having the remote standby database take over as the primary database.
此问题的可能原因是，在hadr超时间隔内主要数据库无法建立与其备用数据库的连接。
The possible cause of this problem is that the primary database failed to establish a connection to its standby within the HADR timeout interval.
创建备用数据库之后，不要使用ROLLFORWARDDATABASE命令作为恢复选项。
Once you have created the standby database, do not use the ROLLFORWARD DATABASE command as a recovery option.
例如，主数据库可以放在一个城市的数据中心中，而备用数据库放在另一个城市的数据中心中。
For example, the primary database might be located at one data center in one city, while the standby database might be located at another data center in another city.
在备用服务器(Node3)上执行以下命令，让这个数据库成为HADR设置的备用数据库。
Execute the following commands on the standby server (Node3) to make this database the standby database for the HADR setup.
要想使用 HADR，必须有两个专用的服务器：一个用于运行主数据库，一个用于备用数据库。
To take advantage of HADR, you must have two dedicated servers available: one for the primary database and one for the standby database.
如果高可用性集群中某一个服务器出故障，那么集群软件就会将工作负载转移到idle备用数据库服务器。
If one of the servers in the high availability cluster fails, then the clustering software transfers the workload to the idle standby database server.
在此情况下，您需要将主要计算机上的数据库作为备用数据库启动，以便这两个数据库重新保持同步。
In this situation, you need to start the database on the primary machine as the standby to get the two databases back in sync again.
为了使备用数据库尽可能最新，应该不断地将源数据库上可用的非活动日志文件应用到备用数据库上。
In order to keep the standby database as current as possible, new inactive log files from the source database should be continually applied on the standby database as they become available.
如果源数据库变得不可用(例如，它崩溃了)，那么可以激活目标系统上的备用数据库，以供用户访问。
If the source database becomes unavailable (for example, if it crashes), the standby database on the target system can be activated for user access.
在接管发生之后，WebSphereApplicationServer将建立到备用数据库的新连接。
Once the takeover takes place, WebSphere Application Server will establish new connections to the standby database.
第12.6节的场景，描述活动的物理备用数据库为读/写报告数据库，然后与主数据库重新同步数据库。
Section 12.6for a scenario that describes activating a physical standby database as a read/write reporting database, and then resynchronizing the database with the primary database.
HADR把数据修改从源数据库(称为主数据库)复制到目标数据库(称为备用数据库)，从而防止数据丢失。
HADR protects against data loss by replicating data changes from a source database, called the primary, to a target database, called the standby.
在备用计算机上，首先禁用数据库，然后发出starthadr命令，将其作为备用数据库启动(清单7)。
On the standby machine, first deactivate the database and then issue the start hadr command to start it as the standby database (Listing 7).
Asynchronous：并不以任何方式推迟提交主数据库上的数据修改，日志记录异步地传输给备用数据库。
Asynchronous: Committing a database change on the primary database is not held up in any way by the communication of log records to the standby database.
这个拓扑结构中的第三个节点(Node3)由远程位置上的灾难恢复站点组成，它托管前面提到的主数据库的备用数据库。
The third node (Node3) in this topology consists of the disaster recovery site existing in a remote location and hosting the standby database for the primary database mentioned earlier.
这个拓扑结构中的第三个节点(Node3)由远程位置上的灾难恢复站点组成，它托管前面提到的主数据库的备用数据库。
The third node (Node3) in this topology consists of the disaster recovery site existing in a remote location and hosting the standby database for the primary database mentioned earlier.
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