这种情况很好解决，只需将没损坏的联机日志拷贝到那个坏的日志去就行。
案例二：非current的联机日志所有成员丢失模拟环境：
1.查看联机日志状态信息
sys@SIQIAN11>select group#,sequence#,archived,status from v$log;
1 4 NO CURRENT
2 2 YES INACTIVE
3 3 YES INACTIVE
sys@SIQIAN11>select member from v$logfile;
/u01/oradata/siqian11g/redo01.log
/u01/oradata/siqian11g/redo03.log
/u01/oradata/siqian11g/redo02.log
2.关闭数据库并删除非当前联机日志
shutdown immediate
[Oracle@siqian siqian11g]$ rm -f /u01/oradata/siqian11g/redo02.log
3.启动数据库并查看出错信息
ORA-00313: open failed for members of log group 2 of thread 1
ORA-00312: online log 2 thread 1: '/u01/oradata/siqian11g/redo02.log'
4.清理第二组日志
sys@SIQIAN11>alter database clear logfile group 2;
5.打开数据库
alter database open;
案例三：current的联机日志所有成员丢失模拟环境：
1.查看联机日志状态信息
sys@SIQIAN11>select group#,sequence#,archived,status from v$log;
GROUP# SEQUENCE# ARC STATUS
-------------------- --- ----------------
1 7 NO CURRENT
2 5 YES INACTIVE
3 6 YES ACTIVE
2.关闭数据库并删除所有第一组的联机日志
shutdown immediate
[oracle@siqian siqian11g]$ rm -f redo01.log
3.启动数据库并查看错误信息
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u01/oradata/siqian11g/redo01.log'
4.尝试用上面的方法清理第一组日志
sys@SIQIAN11>alter database clear logfile group 1;
alter database clear logfile group 1
*
ERROR at line 1:
ORA-00350: log 1 of instance siqian11g (thread 1) needs to be archived
ORA-00312: online log 1 thread 1: '/u01/oradata/siqian11g/redo01.log'
5.不完全恢复数据库
sys@SIQIAN11>recover database until cancel;
Media recovery complete.
6.以resetlogs方式打开数据库
sys@SIQIAN11>alter database open resetlogs;
7.冷备
案例四：数据文件和当前日志组全部丢失模拟环境：
1.查看当前日志信息
sys@SIQIAN11>select group#,sequence#,archived,status from v$log;
GROUP# SEQUENCE# ARC STATUS
-------------------- --- ----------------
1 7 YES ACTIVE
2 8 YES ACTIVE
3 9 NO CURRENT
2.用test用户登录并向t01表加若干数据
test@SIQIAN11>select count(*) from t01;
COUNT(*)
----------
10
test@SIQIAN11>begin
2 for i in 11..15
3 loop
4 insert into t01 values(i);
5 end loop;
6 end;
7 /
PL/SQL procedure successfully completed.
commit;
test@SIQIAN11>select count(*) from t01;
COUNT(*)
----------
15
3.关闭数据库并删除数据文件与当前日志文件
shutdown immediate
[oracle@siqian siqian11g]$ rm -f redo03.log
[oracle@siqian siqian11g]$ rm -f *.dbf
4.启动数据库并查看出错信息
startup
ORA-01157: cannot identify/lock data file 1 - see DBWR trace file
ORA-01110: data file 1: '/u01/oradata/siqian11g/system01.dbf'
sys@SIQIAN11>select file#,error from v$recover_file;
FILE# ERROR
---------------------------------------------------------------------------
1 FILE NOT FOUND
2 FILE NOT FOUND
3 FILE NOT FOUND
4 FILE NOT FOUND
5 FILE NOT FOUND
6 FILE NOT FOUND
7 FILE NOT FOUND
8 FILE NOT FOUND
8 rows selected.
5.还原数据文件
[oracle@siqian siqian11g]$ cp /backup/cold/ *.dbf /u01/oradata/siqian11g/
6.查看控制文件和数据文件中的SCN信息
sys@SIQIAN11>select file#,checkpoint_change# from v$datafile;
FILE# CHECKPOINT_CHANGE#
----------------------------
1 2267395
2 2267395
3 2267395
4 2267395
5 2267395
6 2267395
7 2267395
8 2267395
8 rows selected.
sys@SIQIAN11>select file#,checkpoint_change# from v$datafile_header;
FILE# CHECKPOINT_CHANGE#
----------------------------
1 2266285
2 2266285
3 2266285
4 2266285
5 2266285
6 2266285
7 2266285
8 2266285
8 rows selected.
发现控制文件中的SCN号比较新，因为数据文件是从冷备那边拷贝来的。
7.尝试恢复数据库
sys@SIQIAN11>recover database;
ORA-00283: recovery session canceled due to errors
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/u01/oradata/siqian11g/redo03.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
刚才把当前的日志删除了，所以找不到日志来恢复
8.用until cancel方式来恢复数据库
sys@SIQIAN11>recover database until cancel;
ORA-00279: change 2266772 generated at 06/30/2013 10:14:43 needed for thread 1
ORA-00289: suggestion : /backup/arch/arch_1_819452646_9.log
ORA-00280: change 2266772 for thread 1 is in sequence #9
Specify log: {=suggested | filename | AUTO | CANCEL}
ORA-00308: cannot open archived log '/backup/arch/arch_1_819452646_9.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
查看当前日志信息
sys@SIQIAN11>select group#,sequence#,archived,status from v$log;
GROUP# SEQUENCE# ARC STATUS
-------------------- --- ----------------
1 7 YES INACTIVE
3 9 NO CURRENT
2 8 YES INACTIVE
9.通过基于cancel的不完全恢复来恢复数据库
sys@SIQIAN11>recover database until cancel;
ORA-00279: change 2266772 generated at 06/30/2013 10:14:43 needed for thread 1
ORA-00289: suggestion : /backup/arch/arch_1_819452646_9.log
ORA-00280: change 2266772 for thread 1 is in sequence #9
Specify log: {=suggested | filename | AUTO | CANCEL}
cancel
Media recovery cancelled.
10.以resetlogs方式打开数据库
sys@SIQIAN11>alter database open resetlogs;
11.验证
test@SIQIAN11>select count(*) from t01;
COUNT(*)
----------
10
可见只能恢复到上一次归档的模样。
12.冷备