CLUSTER CONSISTENT mode in AlertSID.log

作者: Fenng | 可以转载, 转载时务必以超链接形式标明文章原始出处和作者信息及版权声明
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前几天发生的事情．系统是 9iR2 的 DataGuard .　注意到 Data Guard 主库上有的时候会在$BDUMP 目录下产生包含如下内容的trace 文件:

......
Destination LOG_ARCHIVE_DEST_2 is in CLUSTER CONSISTENT mode
Destination LOG_ARCHIVE_DEST_2 is in MAXIMUM PERFORMANCE mode
Destination LOG_ARCHIVE_DEST_2 is in CLUSTER CONSISTENT mode
Destination LOG_ARCHIVE_DEST_2 is in MAXIMUM PERFORMANCE mode
Destination LOG_ARCHIVE_DEST_2 is in CLUSTER CONSISTENT mode
......

以前遇到过一次,当时忽略掉了.不过今天忽然感觉之所以产生这样的Log还是比较奇怪的. 找了半天 Metalink ,发现还真有对这个现象的解释:

This message indicates that the LGWR is sending archivelogs to the standby database from a primary database that is in "cluster consistency" mode. This means that information maintained in the archivelogs is used for thread merging during failover to correctly synchronize the standby database to a transactionally consistent point-in-time. This is especially important when using asynchronous network transmittal, as thread merging of asynchronously transmitted archivelogs is very difficult.
This message has nothing to do with whether or not you actually have a standby database.
This message indicates the redo is being setup in case you have a standby database.

放心了许多. 参见Metalink Note:214986.1

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