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最新推荐文章于 2025-12-26 18:13:00 发布

转载最新推荐文章于 2025-12-26 18:13:00 发布 · 115 阅读

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    对于 DG ，我还是有比较多的困惑的。
    这里先记录下一些注意事项，后期再慢慢整理了。
    1、当使用 standby log 时，standby log 的大小要和 primary db 的 redo log 大小要一致（或者比 primary db 的redo log 大）。
    If you have configured a standby redo log on one or more standby databases in the configuration, ensure the size of the current standby redo log file on each standby database exactly matches the size of the current online redo log file on the primary database.
    At log switch time, if there are no available standby redo log files that match the size of the new current online redo log file on the primary database:
    The primary database will shut down if it is operating in maximum protection mode, or the primary database will change to maximum performance mode if it is operating in maximum availability mode.
    The RFS process on the standby database will create an archived redo log file on the standby database and write the following message in the alert log:
No standby log files of size blocks available.
    For example, if the primary database uses two online redo log groups whose log files are 100K and 200K, respectively, then the standby database should have 4 standby redo log groups with log file sizes of 100K and 200K
    Soruce :http://download.oracle.com/docs/cd/B14117_01/server.101/b10823/troubleshooting.htm
    2、最大保护和最大可用，一定要有 standby log ，最大性能时，当使用 arch 传输的时候，不需要 standby log，当使用 lgwr 传输时，需要 standby log。
    3、创建 standby log 的时候，不要轻易指定 thread，如下：
    ALTER DATABASE ADD STANDBY LOGFILE THREAD 5 ('/oracle/dbs/log1c.rdo','/oracle/dbs/log2c.rdo') SIZE 500M;
    否则，standby log 将有可能不被使用，alert.log 文件中，会报如下错误：
    RFS[6]: No standby redo logfiles of size n blocks available
    查看 v$standby_log.status 也会显示 UNASSIGNED