oracle redo日志恢复
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Oracle备份恢复中，redo的恢复相对来说还是比较简单的，只要保证每组的成员不止一个，出现问题的几率就相当小，即使出了问题我们也可按照不同的方法将他们恢复，所以如果碰到日志文件损坏，完全不必紧张！按照下面的方法来做，基本上都能搞定！ 试验一：用命令清空日志组方法 1、 查看原来表中数据 SQL> conn test/test Connected. SQL> select * from test; TEL ---------- 1 2 3 2 、插入新数据 SQL> insert into test values(4); 1 row created. SQL> commit; Commit complete. SQL> 3、 正常关闭数据库 4、 利用 os command 删除所有 redo 文件 5、 启动数据库 SQL> startup ORACLE instance started. Total System Global Area 353862792 bytes Fixed Size 730248 bytes Variable Size 285212672 bytes Database Buffers 67108864 bytes Redo Buffers 811008 bytes Database mounted. ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/T3/ORACLE/oradata/ORA9/redo01.log' 6、 查看当前日志状态 SQL> select * from v$log; GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS ---------- ---------- ---------- ---------- ---------- --- ---------------- FIRST_CHANGE# FIRST_TIME ------------- ---------- 1 1 2 104857600 1 YES INACTIVE 487837 01-9 月 -05 2 1 4 104857600 1 NO CURRENT 487955 01-9 月 -05 3 1 3 104857600 1 YES INACTIVE 487839 01-9 月 -05 看来 redo01.log 不是当前日志，对于这类非当前日志可以直接 clear, 系统会重新自动生成一个 redo 文件 7 、 SQL> alter database clear logfile group 1; Database altered. 7、 继续启动 db SQL> alter database open; alter database open * ERROR at line 1: ORA-00313: open failed for members of log group 2 of thread 1 ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log' 8、 看来 redo 也得恢复，但是 redo02 是当前 redo, 直接 clear 是不行的 SQL> alter database clear logfile group 2; alter database clear logfile group 2 * ERROR at line 1: ORA-00350: log 2 of thread 1 needs to be archived ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log' 9、 按照 oracle 的某些做法也是不行的 SQL> alter database clear unarchived logfile group 2 unrecoverable datafile; alter database clear unarchived logfile group 2 unrecoverable datafile * ERROR at line 1: ORA-00313: open failed for members of log group 2 of thread 1 ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log' ORA-27037: unable to obtain file status SVR4 Error: 2: No such file or directory Additional information: 3 10、 尝试从其他冷被分 cp 过来一个，再作 clear, 还是不行 SQL> host cp /T3/ORACLE/oradata2/ORA9/redo02.log /T3/ORACLE/oradata/ORA9/ SQL> alter database clear unarchived logfile group 2 unrecoverable datafile; alter database clear unarchived logfile group 2 unrecoverable datafile * ERROR at line 1: ORA-00322: log 2 of thread 1 is not current copy ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log' SQL> 11、 但是对于非当前日志就都可以，下面看看 redo03 SQL> alter database clear logfile group 3; Database altered. 结论： 如果数据库是 正常 shutdown, 非当前日志都可以直接 clear 来重新生成，而且不丢失数据，因为正常关闭 db, 数据已经写入 dbf 文件了。唯独当前日志不可以，当前日志必须用其他方法恢复，不管是不是正常关闭， 方法二：用 cancel 模式恢复数据库 前面的出错提示，步骤都一样，唯独恢复的方法不一样 SQL> startup ORACLE instance started. Total System Global Area 353862792 bytes Fixed Size 730248 bytes Variable Size 285212672 bytes Database Buffers 67108864 bytes Redo Buffers 811008 bytes Database mounted. ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/T3/ORACLE/oradata/ORA9/redo01.log' 看看丢失了哪些 redo SQL> host ls /T3/ORACLE/oradarta/ORA9/redo* /T3/ORACLE/oradarta/ORA9/redo*: No such file or directory 看来 redo 都丢了 直接 recover SQL> recover database until cancel; Media recovery complete. 这个时候 redo 还没有生成 SQL> host ls /T3/ORACLE/oradata/ORA9/redo* /T3/ORACLE/oradata/ORA9/redo*: No such file or directory 启动数据库 SQL> alter database open ; alter database open * ERROR at line 1: ORA-01589: must use RESETLOGS or NORESETLOGS option for database open SQL> alter database open resetlogs; Database altered. （注意，这里必须用 resetlogs, 否则会错误的 SQL> alter database open noresetlogs; alter database open noresetlogs * ERROR at line 1: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/T3/ORACLE/oradata/ORA9/redo01.log' SQL> Resetlogs 其实就是根据控制文件让系统自动重新生成 redo, 如果 noresetlog 的话，就不会重新生成 redo, 缺少了文件， db 自然无法启动） SQL> host ls /T3/ORACLE/oradata/ORA9/redo* /T3/ORACLE/oradata/ORA9/redo01.log /T3/ORACLE/oradata/ORA9/redo02.log /T3/ORACLE/oradata/ORA9/redo03.log SQL> 检验 SQL> select * from test.test; TEL ---------- 1 2 3 4 SQL> 数据一点儿都没有丢失 结论： 如果数据库是正常关闭的，用 recover database until cancel 可以轻松恢复或者说重新建立所有的 redo ，不再区分是否是当前日志，而且由于正常关闭，不会丢失任何数据，唯一可能丢失的情况就是如果日志还没有归档 这种恢复方法 由于要 resetlogs, 所以在恢复完成后，日志清零，以前的备份不再起作用，所以建议立即备份 SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination /T3/ORACLE/arch Oldest online log sequence 0 Next log sequence to archive 1 Current log sequence 1 SQL>
实验三：通过重新生成控制文件来恢复 redo 前面的都一样，只是处理方法不一样 SQL> startup ORACLE instance started. Total System Global Area 353862792 bytes Fixed Size 730248 bytes Variable Size 285212672 bytes Database Buffers 67108864 bytes Redo Buffers 811008 bytes Database mounted. ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/T3/ORACLE/oradata/ORA9/redo01.log' SQL> alter database backup controlfile to trace; Database altered. SQL> shutdown immediate ORA-01109: database not open Database dismounted. ORACLE instance shut down. SQL> 2、 修改一下刚才生成的那个文件 CREATE CONTROLFILE REUSE DATABASE "ORA9" RESETLOGS ARCHIVELOG -- SET STANDBY TO MAXIMIZE PERFORMANCE MAXLOGFILES 50 MAXLOGMEMBERS 5 MAXDATAFILES 100 MAXINSTANCES 1 MAXLOGHISTORY 226 LOGFILE GROUP 1 '/T3/ORACLE/oradata/ORA9/redo01.log' SIZE 100M, GROUP 2 '/T3/ORACLE/oradata/ORA9/redo02.log' SIZE 100M, GROUP 3 '/T3/ORACLE/oradata/ORA9/redo03.log' SIZE 100M -- STANDBY LOGFILE DATAFILE '/T3/ORACLE/oradata/ORA9/system01.dbf', '/T3/ORACLE/oradata/ORA9/undotbs01.dbf', '/T3/ORACLE/oradata/ORA9/cwmlite01.dbf', '/T3/ORACLE/oradata/ORA9/drsys01.dbf', '/T3/ORACLE/oradata/ORA9/example01.dbf', '/T3/ORACLE/oradata/ORA9/indx01.dbf', '/T3/ORACLE/oradata/ORA9/odm01.dbf', '/T3/ORACLE/oradata/ORA9/tools01.dbf', '/T3/ORACLE/oradata/ORA9/users01.dbf', '/T3/ORACLE/oradata/ORA9/xdb01.dbf', '/T3/ORACLE/oradata/ORA9/test01.dbf' CHARACTER SET ZHS16GBK ; 另存为一个脚本，运行他 SQL> @clone.sql Control file created. SQL> alter database open resetlogs; Database altered. SQL> 搞定 …………… 结论：这种方法的关键是重新创建控制文件，后面的步骤和前面的道理一样的 前面的三种方法都是假设 db 是正常关闭的，数据已经写入数据库文件中，所以不会由数据存在 redo 种，所以 clear 的话也不会有数据丢失 本文来自http://www.cublog.cn/u/11765/showart_427753.html （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |