实践redo log 恢复
1.在OS上删除非current redo log
删除后，查询：
没有结果，switch一下：
alert log出现：
无法switch
重启一下DB：
没有报错，再看看alert log：
报错了。
问题：是否自动跳过有问题的group？
再查询：
INVALID了，开始恢复：
再到OS的目录看一下：
看到redo log自动生成回来了，group的状态变成unused。
switch一下：
成功恢复！
2.current
删除group 1的两个member
然后switch一下，alert log显示：
查询一下v$logfile状态，什么都没有看出来
重启一下DB：
打开不了database，好了，开始恢复：
顺利恢复了，看看alert log情况：
OS上的情况
没有问题，文件也自动重建了。
但是有个奇怪的现象：
怎么会是group 3 unused呢？
提醒：alter database open resetlogs;后一定要重新做全备
有时间测试一下current redo log丢失对数据丢失的影响
[root@william01 redob]# ll total 153780 -rw-r----- 1 oracle dba 52429312 Feb 11 10:30 redo01b.log -rw-r----- 1 oracle dba 52429312 Feb 11 11:28 redo02b.log -rw-r----- 1 oracle dba 52429312 Feb 11 10:30 redo03b.log [root@william01 redob]# rm /oracle/data/redob/redo01b.log rm: remove regular file `/oracle/data/redob/redo01b.log'? yes [root@william01 redob]# ll total 102520 -rw-r----- 1 oracle dba 52429312 Feb 11 11:28 redo02b.log -rw-r----- 1 oracle dba 52429312 Feb 11 10:30 redo03b.log
删除后，查询：
SQL> select * from v$logfile;
GROUP# STATUS TYPE MEMBER IS_
---------- ------- ------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---
3 ONLINE /oracle/data/redoa/redo03a.log NO
3 ONLINE /oracle/data/redob/redo03b.log NO
2 ONLINE /oracle/data/redoa/redo02a.log NO
2 ONLINE /oracle/data/redob/redo02b.log NO
1 ONLINE /oracle/data/redoa/redo01a.log NO
1 ONLINE /oracle/data/redob/redo01b.log NO
6 rows selected.
没有结果，switch一下：
SQL> alter system switch logfile;
alert log出现：
Thread 1 advanced to log sequence 24 Current log# 3 seq# 24 mem# 0: /oracle/data/redoa/redo03a.log Current log# 3 seq# 24 mem# 1: /oracle/data/redob/redo03b.log Thu Feb 11 11:30:08 2010 Errors in file /oracle/admin/williamdb/bdump/williamdb_arc0_24908.trc: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/oracle/data/redob/redo01b.log' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory Additional information: 3
无法switch
重启一下DB：
SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORACLE instance started. Total System Global Area 285212672 bytes Fixed Size 1261348 bytes Variable Size 159383772 bytes Database Buffers 117440512 bytes Redo Buffers 7127040 bytes Database mounted. Database opened.
没有报错，再看看alert log：
Thu Feb 11 11:33:37 2010 Errors in file /oracle/admin/williamdb/bdump/williamdb_lgwr_27256.trc: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/oracle/data/redob/redo01b.log' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory Additional information: 3
报错了。
问题：是否自动跳过有问题的group？
再查询：
SQL> select * from v$logfile;
GROUP# STATUS TYPE MEMBER IS_
---------- ------- ------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---
3 ONLINE /oracle/data/redoa/redo03a.log NO
3 ONLINE /oracle/data/redob/redo03b.log NO
2 ONLINE /oracle/data/redoa/redo02a.log NO
2 ONLINE /oracle/data/redob/redo02b.log NO
1 ONLINE /oracle/data/redoa/redo01a.log NO
1 INVALID ONLINE /oracle/data/redob/redo01b.log NO
6 rows selected.
INVALID了，开始恢复：
SQL> alter database clear logfile group 1;
Database altered.
SQL> SELECT * FROM v$logfile;
GROUP# STATUS TYPE MEMBER IS_
---------- ------- ------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---
3 ONLINE /oracle/data/redoa/redo03a.log NO
3 ONLINE /oracle/data/redob/redo03b.log NO
2 ONLINE /oracle/data/redoa/redo02a.log NO
2 ONLINE /oracle/data/redob/redo02b.log NO
1 ONLINE /oracle/data/redoa/redo01a.log NO
1 ONLINE /oracle/data/redob/redo01b.log NO
6 rows selected.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------
1 1 0 52428800 2 YES UNUSED 981183 11-FEB-10
2 1 22 52428800 2 YES INACTIVE 975410 11-FEB-10
3 1 24 52428800 2 NO CURRENT 981210 11-FEB-10
再到OS的目录看一下：
[root@william01 redob]# ll total 153780 -rw-r----- 1 oracle dba 52429312 Feb 11 11:44 redo01b.log -rw-r----- 1 oracle dba 52429312 Feb 11 11:33 redo02b.log -rw-r----- 1 oracle dba 52429312 Feb 11 11:44 redo03b.log [root@william01 redob]#
看到redo log自动生成回来了，group的状态变成unused。
switch一下：
Thread 1 advanced to log sequence 25 Current log# 1 seq# 25 mem# 0: /oracle/data/redoa/redo01a.log Current log# 1 seq# 25 mem# 1: /oracle/data/redob/redo01b.log
成功恢复！
2.current
删除group 1的两个member
[root@william01 redoa]# ll total 153780 -rw-r----- 1 oracle dba 52429312 Feb 11 16:59 redo01a.log -rw-r----- 1 oracle dba 52429312 Feb 11 11:33 redo02a.log -rw-r----- 1 oracle dba 52429312 Feb 11 11:48 redo03a.log [root@william01 redoa]# rm -f redo01a.log [root@william01 redoa]# ll total 102520 -rw-r----- 1 oracle dba 52429312 Feb 11 17:01 redo02a.log -rw-r----- 1 oracle dba 52429312 Feb 11 17:01 redo03a.log [root@william01 redoa]# [root@william01 redoa]# [root@william01 redoa]# cd .. [root@william01 data]# cd redob/ [root@william01 redob]# ll total 153780 -rw-r----- 1 oracle dba 52429312 Feb 11 17:04 redo01b.log -rw-r----- 1 oracle dba 52429312 Feb 11 17:02 redo02b.log -rw-r----- 1 oracle dba 52429312 Feb 11 17:02 redo03b.log [root@william01 redob]# mv redo01b.log redo01b.log.bak [root@william01 redob]# ll total 153780 -rw-r----- 1 oracle dba 52429312 Feb 11 17:05 redo01b.log.bak -rw-r----- 1 oracle dba 52429312 Feb 11 17:02 redo02b.log -rw-r----- 1 oracle dba 52429312 Feb 11 17:02 redo03b.log
然后switch一下，alert log显示：
Thu Feb 11 17:00:20 2010 Errors in file /oracle/admin/williamdb/bdump/williamdb_arc0_27278.trc: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/oracle/data/redoa/redo01a.log' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory Additional information: 3 Thu Feb 11 17:00:20 2010 Errors in file /oracle/admin/williamdb/bdump/williamdb_arc0_27278.trc: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/oracle/data/redoa/redo01a.log' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory Additional information: 3
查询一下v$logfile状态，什么都没有看出来
SQL> select * from v$logfile;
GROUP# STATUS TYPE MEMBER IS_
---------- ------- ------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---
3 ONLINE /oracle/data/redoa/redo03a.log NO
3 ONLINE /oracle/data/redob/redo03b.log NO
2 ONLINE /oracle/data/redoa/redo02a.log NO
2 ONLINE /oracle/data/redob/redo02b.log NO
1 ONLINE /oracle/data/redoa/redo01a.log NO
1 ONLINE /oracle/data/redob/redo01b.log NO
6 rows selected.
重启一下DB：
SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORACLE instance started. Total System Global Area 285212672 bytes Fixed Size 1261348 bytes Variable Size 167772380 bytes Database Buffers 109051904 bytes Redo Buffers 7127040 bytes Database mounted. ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/oracle/data/redoa/redo01a.log' ORA-00312: online log 1 thread 1: '/oracle/data/redob/redo01b.log' SQL> select status from v$instance; STATUS ------------ MOUNTED SQL> alter database open; alter database open * ERROR at line 1: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/oracle/data/redoa/redo01a.log' ORA-00312: online log 1 thread 1: '/oracle/data/redob/redo01b.log'
打开不了database，好了，开始恢复：
SQL> recover database until cancel; Media recovery complete. SQL> alter database open resetlogs; Database altered. SQL> select status from v$instance; STATUS ------------ OPEN
顺利恢复了，看看alert log情况：
Thu Feb 11 17:16:01 2010
Setting recovery target incarnation to 3
Thu Feb 11 17:16:01 2010
Assigning activation ID 3048540245 (0xb5b50855)
Thread 1 advanced to log sequence 2
Thread 1 opened at log sequence 2
Current log# 2 seq# 2 mem# 0: /oracle/data/redoa/redo02a.log
Current log# 2 seq# 2 mem# 1: /oracle/data/redob/redo02b.log
Successful open of redo thread 1
Thu Feb 11 17:16:02 2010
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Thu Feb 11 17:16:02 2010
SMON: enabling cache recovery
Thu Feb 11 17:16:02 2010
Successfully onlined Undo Tablespace 1.
Dictionary check beginning
Dictionary check complete
Thu Feb 11 17:16:02 2010
SMON: enabling tx recovery
Thu Feb 11 17:16:02 2010
Database Characterset is WE8ISO8859P1
replication_dependency_tracking turned off (no async multimaster replication found)
Starting background process QMNC
QMNC started with pid=20, OS id=6516
Thu Feb 11 17:16:03 2010
LOGSTDBY: Validating controlfile with logical metadata
Thu Feb 11 17:16:03 2010
LOGSTDBY: Validation complete
Thu Feb 11 17:16:03 2010
db_recovery_file_dest_size of 100 MB is 0.00% used. This is a
user-specified limit on the amount of space that will be used by this
database for recovery-related files, and does not reflect the amount of
space available in the underlying filesystem or ASM diskgroup.
Thu Feb 11 17:16:05 2010
Starting control autobackup
Control autobackup written to DISK device
handle '/oracle/product/10.2.0/dbs/oraclebackupc-3047744130-20100211-00'
Completed: alter database open resetlogs
OS上的情况
[root@william01 redob]# ll total 205040 -rw-r----- 1 oracle dba 52429312 Feb 11 17:16 redo01b.log -rw-r----- 1 oracle dba 52429312 Feb 11 17:05 redo01b.log.bak -rw-r----- 1 oracle dba 52429312 Feb 11 17:16 redo02b.log -rw-r----- 1 oracle dba 52429312 Feb 11 17:16 redo03b.log [root@william01 redob]#
没有问题，文件也自动重建了。
但是有个奇怪的现象：
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------
1 1 1 52428800 2 YES INACTIVE 1001509 11-FEB-10
2 1 2 52428800 2 NO CURRENT 1001510 11-FEB-10
3 1 0 52428800 2 YES UNUSED 0
SQL> select * from v$logfile;
GROUP# STATUS TYPE MEMBER IS_
---------- ------- ------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---
3 ONLINE /oracle/data/redoa/redo03a.log NO
3 ONLINE /oracle/data/redob/redo03b.log NO
2 ONLINE /oracle/data/redoa/redo02a.log NO
2 ONLINE /oracle/data/redob/redo02b.log NO
1 ONLINE /oracle/data/redoa/redo01a.log NO
1 ONLINE /oracle/data/redob/redo01b.log NO
6 rows selected.
怎么会是group 3 unused呢？
提醒：alter database open resetlogs;后一定要重新做全备
有时间测试一下current redo log丢失对数据丢失的影响