oracle日志文件和控制文件损坏的恢复：
恢复步骤：
1.加入_allow_resetlogs_corruption=true，_corrupted_rollback_segments=true，_offline_rollback_segments=true，启动到nomount
2.利用控制文件的备份，，进行脚本重建，由于current状态redo损坏，所以要resetlogs重建
3.重建后通过alter database open resetlogs;打开数据库，这种情况会丢失在redo中相关事务的数据
备份控制文件并模拟故障：
sql> set linesize 150
sql> alter database backup controlfile to trace as '/home/oracle/ctl.ctl' reuse;
database altered.
sql> insert into tb1 values (1);
1 row created.
sql> commit;
commit complete.
sql> select * from v$log;
group# thread# sequence# bytes members arc status first_change# first_time
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- -------------------
1 1 1 536870912 1 yes inactive 1.2269e+11 2013-05-03 16:08:03
2 1 2 536870912 1 yes inactive 1.2269e+11 2013-05-03 16:23:48
3 1 3 536870912 1 no current 1.2269e+11 2013-05-11 07:26:45
4 1 0 536870912 1 yes unused 0
5 1 0 536870912 1 yes unused 0
sql> shutdown abort;
oracle@readerlogdb-> rm -f redo03.log
oracle@readerlogdb-> rm -f control01.ctl control02.ctl control03.ctl
通过加入相关参数启动到nomount状态：
sql> conn /as sysdba
connected to an idle instance.
sql> startup;
oracle instance started.
total system global area 5049942016 bytes
fixed size 2090880 bytes
variable size 1375733888 bytes
database buffers 3657433088 bytes
redo buffers 14684160 bytes
ora-00205: error in identifying control file, check alert log for more info
sql> create pfile='/home/oracle/pfile.ora' from spfile;
在备份的pfile中加入以下三行：
*._allow_resetlogs_corruption=true
*._corrupted_rollback_segments=true
*._offline_rollback_segments=true
noresetlogs和resetlogs在此实验中的区别：
sql>create controlfile reuse database skyread noresetlogs force logging archivelog
maxlogfiles 20
maxlogmembers 5
maxdatafiles 1000
maxinstances 8
maxloghistory 2337
logfile
group 1 '/database/oradata/skyread/redo01.log' size 512m,
group 2 '/database/oradata/skyread/redo02.log' size 512m,
group 3 '/database/oradata/skyread/redo03.log' size 512m,
group 4 '/database/oradata/skyread/redo04.log' size 512m,
group 5 '/database/oradata/skyread/redo05.log' size 512m
datafile
'/database/oradata/skyread/system01.dbf',
'/database/oradata/skyread/tbs_test.dbf',
'/database/oradata/skyread/sysaux01.dbf',
'/database/oradata/skyread/users01.dbf',
'/database2/oradata/skyread/tbs_mrpmusic01.dbf',
'/database/oradata/skyread/sf01.dbf',
'/database2/oradata/skyread/undotbs02'
character set utf8;