关于RMAN备份数据块一致性的讨论

最新推荐文章于 2022-08-02 10:35:41 发布

RXiaoHong

最新推荐文章于 2022-08-02 10:35:41 发布

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分类专栏： Cla_Mysql

本文链接：https://blog.youkuaiyun.com/RedeLego/article/details/89077616

本文详细讨论了RMAN备份数据块一致性和不一致性的概念。一致备份发生在数据库关闭时，确保所有重做已应用于数据文件。不一致备份则在数据库开放或遇到异常关闭时发生，需要介质恢复。RMAN在归档模式下可进行非一致备份，但NOARCHIVELOG模式下不允许。文章还解释了快照控制文件如何确保备份期间的读取一致性，并强调了备份归档日志和控制文件的重要性。

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原关于 RMAN 备份数据块一致性的讨论https://blog.youkuaiyun.com/tianlesoftware/article/details/5800172版权声明： https://blog.youkuaiyun.com/tianlesoftware/article/details/5800172
今天和杭州恒生的一个朋友讨论一个RMAN 在备份时数据块一致性的问题。
关于RMAN 的备份原理参考blog：
RMAN 系列（一）---- RMAN 体系结构概述
http://www.cndba.cn/Dave/article/1165
先看官方文档上的一段话：
Consistent Backups
You can use the BACKUP command to make consistent and inconsistent backups of the database. A consistent backup occurs when the database is in a consistent state. A database is in a consistent state after being shut down with the SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL commands. A consistent shutdown guarantees that all redo has been applied to the datafiles. If you mount the database and make a backup at this point, then you can restore the database backup later and open it without performing media recovery.
Inconsistent Backups
Any database backup that is not consistent is an inconsistent backup. A backup made when the database is open is inconsistent, as is a backup made after an instance failure or SHUTDOWN ABORT command. When a database is restored from an inconsistent backup, Oracle Database must perform media recovery before the database can be opened, applying any pending changes from the redo logs.
Note:
RMAN does not permit you to make inconsistent backups when the database is in NOARCHIVELOG mode. If you employ user-managed backup techniques for a NOARCHIVELOG database, then you must not make inconsistent backups of this database.
If the database runs