cat /u01/app/oracle/oradata/ENMOEDU/redo03*；
--查看物理地址，查看是否生成文件
SQL>select GROUP#,members,BYTES/1024/1024 size_M,STATUS,ARCHIVED from v$log;
--查看日志组及成员
Alert日志中的错误:
Errors in file
/u01/app/oracle/diag/rdbms/enmoedu/ENMOEDU/trace/ENMOEDU_lgwr_35031.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/ENMOEDU/redo01.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Errors in file /u01/app/oracle/diag/rdbms/enmoedu/ENMOEDU/trace/ENMOEDU_lgwr_35031.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/ENMOEDU/redo01.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
2）.丢失当前redo日志组
select a.group#, a.status, a.archived,b.member
from v$log a,v$logfile b
where a.group#=b.group#;
$rm /u01/app/oracle/oradata/ENMOEDU/redo09*；
alter system switch logfile;
/
/
数据库出现hanging现象，在alert.log中报错；
或重启数据库触发错误：
Sql> shutdown immediate
Sql> startup
--触发出错
SQL> startup mount
ORACLE instance started.
Total System Global Area 237998080 bytes
Fixed Size 2227216 bytes
Variable Size 192938992 bytes
Database Buffers 37748736 bytes
Redo Buffers 5083136 bytes
Database mounted.
SQL> alter database clear logfile group 9;
--丢失current状态日志组，不能这样恢复
alter database clear logfile group 9
*
ERROR at line 1:
ORA-00350: log 9 of instance ENMOEDU (thread 1) needs to be archived
ORA-00312: online log 9 thread 1: '/u01/app/oracle/oradata/ENMOEDU/redo03.log'
SQL> alter database clear unarchived logfile group 9;
--无归档恢复
Database altered.
验证：
!ls /u01/app/oracle/oradata/ENMOEDU/
SQL> select GROUP#,members,BYTES/1024/1024 size_M,STATUS,ARCHIVED from v$log;
----------------------------------------------------------------------------------------------------------------
二、丢失临时文件：
1.--查看临时文件的位置及名称
SYS>select name from v$tempfile;
/u01/app/oracle/oradata/PROD/datafile/o1_mf_temp_b22570tq_.tmp
2.--删除临时文件
SYS>！rm /u01/app/oracle/oradata/PROD/datafile/o1_mf_temp_b22570tq_.tmp
3.--触发错误，临时文件未找到
SYS>create global temporary table tab_temp as select * from dba_objects;
create global temporary table tab_temp as select * from dba_objects
*
ERROR at line 1:
ORA-01116: error in opening database file 201
ORA-01110: data file 201:
'/u01/app/oracle/oradata/PROD/datafile/o1_mf_temp_b22570tq_.tmp'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
4.在知道临时数据文件丢失时，可以不需要重新启动数据库就可以在丢失了临时文件后进行恢复；
SQL> ALTER TABLESPACE temp ADD TEMPFILE '/u01/app/oracle/oradata/orcl/temp02.dbf' SIZE 20M;
Tablespace altered.
SQL> ALTER TABLESPACE temp DROP TEMPFILE '/u01/app/oracle/oradata/orcl/temp01.dbf';
Tablespace altered.
5. 1）在11g中还可以重启数据库，数据库会自动重建临时数据文件，可以查看alert日志看相关信息(一般直接第4步就可以了)
shutdown immediate;
SYS>startup
ORACLE instance started.
Total System Global Area 839282688 bytes
Fixed Size 2257880 bytes
Variable Size 545262632 bytes
Database Buffers 289406976 bytes
Redo Buffers 2355200 bytes
Database mounted.
Database opened.
SYS>select name from v$tempfile;
/u01/app/oracle/oradata/PROD/datafile/o1_mf_temp_b29o0g6r_.tmp
1 row selected.
--数据库重建
2）在11g以前，如数据库不能重起，可以创建新的临时表空间：
create temporary tabl