Back Up with RMAN

最新推荐文章于 2023-09-11 08:32:33 发布

m_linda

最新推荐文章于 2023-09-11 08:32:33 发布

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本文链接：https://blog.youkuaiyun.com/m_linda/article/details/38977561

本文介绍了RMAN备份相关知识。包括备份概念，如用户管理备份、服务器管理备份等；可备份的文件类型，如数据文件、控制文件等；不能备份的文件，如临时文件、在线重做日志文件等；RMAN能生成的三种备份类型，即备份集、压缩备份集和镜像副本；还提及了RMAN存储库的相关信息。

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1. Backup Concepts

User-managed backup

Server-managed backup

Closed backup --- cold, consistent, offline --- the database must be in mount mode, following a clean shutdown

Open backup --- hot, inconsistent, online --- can only be made if the database is in archivelog mode

Whole backup

Partial backup --- can only be made if the database is in archivelog mode.

Full backup

Incremental backup --- cumulative / differential --- can be made with server-managed backups, but not with user-managed backups, must always be as backup
sets or compressed backup sets.

Incremental level 0 backup
Incremental level 1 backup:extract all blocks that have changed since the last level 1 backup, or the last level 0 backup if there have been no intervening level 1 backups.
cumulative backup:extract all blocks that have changed since the last level 0 backup, irrespective of whether there have been any level 1 backups in the meantime.

2. The file types that can be backed up by RMAN

Datafiles
Controlfile
Archive redo log files
SPFILE
Backup set pieces

3. Files that cannot be backed up by RMAN

Tempfiles
Online redo log files
Password file
Static PFILE
Oracle Net configuration files

4. RMAN can generate three types of backup

A backup set is a proprietary format that can contain several files and will not include blocks of a datafile that are not currently part of a segment --- full or incremental
A compressed backup set has the same content as a backup set, but RMAN will apply a compression algorithm as it writes out the backup set --- full or incremental
An image copy is a backup file that is identical to the input file. An image copy is immediately interchangeable with its source, whereas to extract a file from a backup set requires an RMAN restore operation --- full
- RMAN reads and writes in Oracle blocks, not operating system blocks.
- This means that many of the great features of backup sets (such as incremental backup, compression, writing directly to tape, or controlling the size of the output pieces) cannot be used.
- A restore can be very fast, because there is no need to extract the file from a backup set.
- Tape channels cannot be used for image copies.

5. RMAN repository

The RMAN repository is metadata about backups, it is stored in the controlfile of the target database, and optinally in a set of tables created in a catalog database.