我们一般使用’date -s’命令来修改系统时间。比如将系统时间设定成2011年8月24日的命令如下。
#date -s 08/24/2011
将系统时间设定成下午23点0分20秒的命令如下。
#date -s 23:00:20
注意，这里说的是系统时间，是linux由操作系统维护的。
在系统启动时，Linux操作系统将时间从CMOS中读到系统时间变量中，以后修改时间通过修改系统时间实现。为了保持系统时间与CMOS时间的一致性，Linux每隔一段时间会将系统时间写入CMOS。由于该同步是每隔一段时间（大约是11分钟）进行的，在我们执行date -s后，如果马上重起机器，修改时间就有可能没有被写入CMOS,这就是问题的原因。如果要确保修改生效可以执行如下命令。
#clock -w
这个命令强制把系统时间写入CMOS。
Daily Archives: 2011 年 08 月 24 日
当前联机日志损坏恢复
环境模拟
删除状态为active的联机日志，然后强行关闭数据库
处理过程
SQL> startup
ORACLE instance started.
Total System Global Area 167772160 bytes
Fixed Size 1260720 bytes
Variable Size 142607184 bytes
Database Buffers 16777216 bytes
Redo Buffers 7127040 bytes
Database mounted.
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: ‘/u01/oradata/xienfei/redo01.log’
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
Alert.log 日志中错误
Wed Aug 24 00:26:33 2011
Errors in file /u01/admin/xienfei/udump/xff_ora_9186.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: ‘/u01/oradata/xienfei/redo01.log’
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
xff_ora_9186.trc文件中错误
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: ‘/u01/oradata/xienfei/redo01.log’
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
查询当前日志组状态
SQL> select a.group#,a.status,b.member from v$log a,v$logfile b where a.group#=b.group#;
GROUP# STATUS MEMBER
———- —————- ———————————————
1 CURRENT /u01/oradata/xienfei/redo01.log
3 INACTIVE /u01/oradata/xienfei/redo03.log
2 ACTIVE /u01/oradata/xienfei/redo02.log
尝试删除redo日志
SQL> alter database drop logfile group 1;
alter database drop logfile group 1
*
ERROR at line 1:
ORA-01623: log 1 is current log for instance xff (thread 1) – cannot drop
ORA-00312: online log 1 thread 1: ‘/u01/oradata/xienfei/redo01.log’
发现是当前日志不能被删除，尝试切换日志
SQL> alter system switch logfile;
alter system switch logfile
*
ERROR at line 1:
ORA-01109: database not open
在数据库未打开状态，不能切换日志，只能尝试清空日志
SQL> alter database clear unarchived logfile group 1;
alter database clear unarchived logfile group 1
*
ERROR at line 1:
ORA-01624: log 1 needed for crash recovery of instance xff (thread 1)
ORA-00312: online log 1 thread 1: ‘/u01/oradata/xienfei/redo01.log’
因为数据库恢复需要使用，不能被清空，尝试不完成恢复
SQL> recover database until cancel;
ORA-00279: change 1272687 generated at 08/24/2011 00:20:05 needed for thread 1
ORA-00289: suggestion : /u01/archive/1_27_756841839.arc
ORA-00280: change 1272687 for thread 1 is in sequence #27
Specify log: {
auto
ORA-00279: change 1272903 generated at 08/24/2011 00:25:17 needed for thread 1
ORA-00289: suggestion : /u01/archive/1_28_756841839.arc
ORA-00280: change 1272903 for thread 1 is in sequence #28
ORA-00278: log file ‘/u01/archive/1_27_756841839.arc’ no longer needed for this
recovery
ORA-00308: cannot open archived log ‘/u01/archive/1_28_756841839.arc’
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: ‘/u01/oradata/xienfei/system01.dbf’
已经提示数据不一致，尝试着打开数据库
SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: ‘/u01/oradata/xienfei/system01.dbf’
创建pfile文件，添加隐含参数，使之不进行检查点一致性校验
SQL> create pfile=’/tmp/pfile’ from spfile;
File created.
修改pfile ，添加以下参数
*._allow_resetlogs_corruption=TRUE
*._allow_error_simulation=TRUE
SQL> shutdown abort
ORACLE instance shut down.
使用pfile打开数据库
SQL> startup pfile=’/tmp/pfile’
ORACLE instance started.
Total System Global Area 167772160 bytes
Fixed Size 1260720 bytes
Variable Size 150995792 bytes
Database Buffers 8388608 bytes
Redo Buffers 7127040 bytes
Database mounted.
ORA-38760: This database instance failed to turn on flashback database
发现flashback导致数据库不能被正常打开，尝试关闭它
SQL> alter database flashback off;
Database altered.
尝试直接open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
根据提示，使用resetlogs打开数据库
SQL> alter database open resetlogs;
Database altered.
查询日志状态
SQL> select a.group#,a.status,b.member from v$log a,v$logfile b where a.group#=b.group#;
GROUP# STATUS MEMBER
———- —————- ———————————————
3 UNUSED /u01/oradata/xienfei/redo03.log
2 UNUSED /u01/oradata/xienfei/redo02.log
1 CURRENT /u01/oradata/xienfei/redo01.log
因为group1错误，而当前日志组在group 1上，所以切换日志组
SQL> alter system switch logfile;
System altered.
SQL> select a.group#,a.status,b.member from v$log a,v$logfile b where a.group#=b.group#;
GROUP# STATUS MEMBER
———- —————- ———————————————
3 UNUSED /u01/oradata/xienfei/redo03.log
2 CURRENT /u01/oradata/xienfei/redo02.log
1 ACTIVE /u01/oradata/xienfei/redo01.log
SQL> alter system checkpoint;
System altered.
SQL> select a.group#,a.status,b.member from v$log a,v$logfile b where a.group#=b.group#;
GROUP# STATUS MEMBER
———- —————- ———————————————
3 UNUSED /u01/oradata/xienfei/redo03.log
2 CURRENT /u01/oradata/xienfei/redo02.log
1 INACTIVE /u01/oradata/xienfei/redo01.log
删除有问题的group 1日志组
SQL> alter database drop logfile group 1;
Database altered.
SQL> alter system switch logfile;
System altered.
添加日志组并检查是否正确
SQL> select a.group#,a.status,b.member from v$log a,v$logfile b where a.group#=b.group#;
GROUP# STATUS MEMBER
———- —————- ———————————————
3 CURRENT /u01/oradata/xienfei/redo03.log
2 ACTIVE /u01/oradata/xienfei/redo02.log
SQL> alter database add logfile group 1 ‘/u01/oradata/xienfei/redo01.log’ size 50m reuse;
Database altered.
SQL> alter system switch logfile;
System altered.
SQL> select a.group#,a.status,b.member from v$log a,v$logfile b where a.group#=b.group#;
GROUP# STATUS MEMBER
———- —————- ———————————————
3 ACTIVE /u01/oradata/xienfei/redo03.log
2 ACTIVE /u01/oradata/xienfei/redo02.log
1 CURRENT /u01/oradata/xienfei/redo01.log
注意：根据oracle官方建议，使用oracle隐含参数运行数据库可能存在很多不稳定因素，建议立即导出数据库数据，然后新建库，重新导入数据
数据库open状态下日志异常处理
一、环境模拟
删除INACTIVE状态redo日志的物理文件，然后进行大批量事务操作
二、出现现象
1、alert.log记录
Tue Aug 23 23:32:02 2011
Errors in file /u01/admin/xienfei/bdump/xff_arc1_8773.trc:
ORA-00313: Message 313 not found; No message file for product=RDBMS, facility=ORA; arguments: [3] [1]
ORA-00312: Message 312 not found; No message file for product=RDBMS, facility=ORA; arguments: [3] [1] [/u01/oradata/xienfei/redo03.log]
ORA-27037: Message 27037 not found; No message file for product=RDBMS, facility=ORA
Linux Error: 2: No such file or directory
Additional information: 3
2、xff_arc1_8773.trc文件中内容
*** 2011-07-18 18:35:32.071 59526 kcrr.c
kcrrfail: dest:2 err:12541 force:0 blast:1
ORA-00313: Message 313 not found; No message file for product=RDBMS, facility=ORA; arguments: [3] [1]
ORA-00312: Message 312 not found; No message file for product=RDBMS, facility=ORA; arguments: [3] [1] [/u01/oradata/xienfei/redo03.log]
ORA-27037: Message 27037 not found; No message file for product=RDBMS, facility=ORA
Linux Error: 2: No such file or directory
三、处理过程
1、由alert中的redo文件路径，查询group#
SQL> select group#,member from v$logfile;
GROUP# MEMBER
———- ———————————————
3 /u01/oradata/xienfei/redo03.log
2 /u01/oradata/xienfei/redo02.log
1 /u01/oradata/xienfei/redo01.log
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 16 ACTIVE
2 17 CURRENT
3 15 INACTIVE
2、确定是inactive状态的redo日志，直接删除该日志组
SQL> alter database drop logfile group 3;
alter database drop logfile group 3
*
ERROR at line 1:
ORA-00350: log 3 of instance xff (thread 1) needs to be archived
ORA-00312: online log 3 thread 1: ‘/u01/oradata/xienfei/redo03.log’
3、删除失败，提示该日志需要归档，然后直接强行执行清空redo操作
SQL> alter database clear logfile group 3;
alter database clear logfile group 3
*
ERROR at line 1:
ORA-00350: log 3 of instance xff (thread 1) needs to be archived
ORA-00312: online log 3 thread 1: ‘/u01/oradata/xienfei/redo03.log’
4、还不行，加大力度，直接清空并不归档
SQL> ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3;
Database altered.
5、再删除group 3
SQL> alter database drop logfile group 3;
alter database drop logfile group 3
*
ERROR at line 1:
ORA-01623: log 3 is current log for instance xff (thread 1) – cannot drop
ORA-00312: online log 3 thread 1: ‘/u01/oradata/xienfei/redo03.log’
6、还是失败，根据提示查看该日志组当前状态
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 16 INACTIVE
2 17 ACTIVE
3 18 CURRENT
7、切换日志组
SQL> alter system switch logfile;
System altered.
8、查看状态，并处理置于INACTIVE状态
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 19 CURRENT
2 17 ACTIVE
3 18 ACTIVE
SQL> alter system checkpoint;
System altered.
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 19 CURRENT
2 17 INACTIVE
3 18 INACTIVE
9、再次删除归档group 3
SQL> alter database drop logfile group 3;
alter database drop logfile group 3
*
ERROR at line 1:
ORA-00350: log 3 of instance xff (thread 1) needs to be archived
ORA-00312: online log 3 thread 1: ‘/u01/oradata/xienfei/redo03.log’
10、再次清空日志并不归档
SQL> ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3;
Database altered.
11、查询状态
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 19 CURRENT
2 17 INACTIVE
3 0 UNUSED
12、再次删除group 3
SQL> alter database drop logfile group 3;
Database altered.
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 19 CURRENT
2 17 INACTIVE
13、删除丢失的group 3成功，需要添加一组日志
SQL> alter database add logfile group 3 ‘/u01/oradata/xienfei/redo03.log’ size 50m reuse;
Database altered.
14、核实是否正常
SQL> alter system switch logfile;
System altered.
SQL> /
System altered.
SQL> /
System altered.
SQL> select group#,sequence#,status from v$log;
GROUP# SEQUENCE# STATUS
———- ———- —————-
1 22 CURRENT
2 21 ACTIVE
3 20 INACTIVE
