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标题: Oracle备份&RMAN从零开始--fuzzy backup [打印本页]

作者: libydwei2007 时间: 2011-12-22 08:54
标题: Oracle备份&RMAN从零开始--fuzzy backup

A fuzzy backup is a secondary (or backup) copy of data file(s) or directories that were in one state when the backup started, but in a different state by the time the backup completed. This may result in the backup copy being unusable because of the data inconsistencies. Although the backup process might have seemed successful, the resultant copies of the files or directories could be useless because a restore would yield inconsistent and unusable data.

模糊备份，是指对一个数据文件的拷贝。备份开始和结束是处于不同的状态，由于数据处于不一致状态可能导致文件不可用。虽然备份看起来可能是成功的。但是这样的备份可能导致不一致或者完全不可用的数据。

SQL> archive log list;
Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     73
Current log sequence           75

SQL> conn test/test
Connected.

数据库运行过程中进行的拷贝。
SQL> !cp /oradata_2/oradata/tp_test.dbf tp_test.dbf.bak

进行创建表等操作
SQL> create table after_bak(aa varchar2(20));

Table created.
SQL> insert into after_bak values('test');

1 row created.

SQL> commit;

Commit complete.

关闭数据库，并恢复之前的备份后，重新打开数据库。

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> !cp ~/tp_test.dbf.bak /oradata_2/oradata/tp_test.dbf

SQL> startup
ORACLE instance started.

Total System Global Area 285212672 bytes
Fixed Size                  1218968 bytes
Variable Size              75499112 bytes
Database Buffers          201326592 bytes
Redo Buffers                7168000 bytes
Database mounted.
ORA-01113: file 4 needs media recovery
ORA-01110: data file 4: '/oradata_2/oradata/tp_test.dbf'
注意，这里提示我们，第四个文件需要介质恢复。这个正是我们拷贝的数据文件tp_test.dbf.

SQL> recover
Media recovery complete.

SQL> alter database open;

Database altered.
SQL> select * from after_bak;

AA
--------------------
alert_orcl.log 内容：
WARNING! Recovering data file 4 from a fuzzy backup. It might be an online
backup taken without entering the begin backup command.

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