关于备份恢复一直是所有关系型数据库的重头戏。下面会介绍冷备数据库,并模拟破坏数据文件进行恢复数据库,并涉及到其他相关内容
关于备份恢复一直是所有关系型数据库的重头戏。下面会介绍冷备数据库,并模拟破坏数据文件进行恢复数据库,并涉及到其他相关内容。
[Oracle@localhost ~]$ cat /etc/RedHat-release
Red Hat Enterprise Linux Server release 5.5 (Tikanga)
SQL> select * from v$version where rownum
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
首先介绍一下冷备份(完全脱机备份),需要把数据库shutdown后,粘贴复制就可了,先备份先:
SQL> shutdown immediate;
数据库已经关闭。
已经卸载数据库。
ORACLE 例程已经关闭。
[oracle@localhost orcl3939]$ cp *.dbf /home/oracle/beifeng
[oracle@localhost orcl3939]$ cp *.log /home/oracle/beifeng
[oracle@localhost orcl3939]$ cp *.ctl /home/oracle/beifeng
控制文件只需要备份一份就行了,因为是镜像文件,完全一样。
是不是很简单!
这种方式适合archivelog和noarchivelog,其中涉及到了几类文件:
logfile:v$log v$logfile
controlfile:v$controlfile
datafile:dba_data_files
temp files:dba_temp_files
其中的临时文件并不是我们备份的对象,因为备份文件可以理解成数据库的虚拟内存,如linux中,我们分区时,如果内存较小时,可以分配swap分区,作用是交换缓存数据,作为内存不足的一种选择而已。
关于archivelog和noarchivelog,生产环境中几乎都是archivelog:
SQL> archive log list;
数据库日志模式 非存档模式
自动存档 禁用
存档终点 USE_DB_RECOVERY_FILE_DEST
最早的联机日志序列 424
当前日志序列 426
此时我的练习库是非归档模式,那我们启动归档模式:
SQL> startup mount;
ORACLE 例程已经启动。
SQL> alter database archivelog;
数据库已更改。
SQL> select log_mode from v$database;
LOG_MODE
------------
ARCHIVELOG
此时数据库已经是归档模式。
关于归档文件存放位置,看参数:
SQL> show parameter db_recover
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string /u01/app/oracle/flash_recovery
_area
db_recovery_file_dest_size big integer 3852M
第一个参数是存放位置,第二个参数是该空间的大小。
flash_recovery _area目录是10g才有的,便于管理归档等文件。
我们可以修改db_recovery_file_dest:
SQL> alter system set db_recovery_file_dest =' ';
系统已更改。
SQL> show parameter db_recover
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string
db_recovery_file_dest_size big integer 3852M
此时归档文件存放的目录回到了10g之前:
SQL> show parameter log_archive_dest
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest string
log_archive_dest_1 string
log_archive_dest_10 string
log_archive_dest_11 string
log_archive_dest_12 string
log_archive_dest_13 string
log_archive_dest_14 string
log_archive_dest_15 string
log_archive_dest_16 string
log_archive_dest_17 string
log_archive_dest_18 string
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_19 string
log_archive_dest_2 string
log_archive_dest_20 string
log_archive_dest_21 string
log_archive_dest_22 string
log_archive_dest_23 string
log_archive_dest_24 string
log_archive_dest_25 string
log_archive_dest_26 string
log_archive_dest_27 string
log_archive_dest_28 string
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_29 string
log_archive_dest_3 string
log_archive_dest_30 string
log_archive_dest_31 string
log_archive_dest_4 string
log_archive_dest_5 string
log_archive_dest_6 string
log_archive_dest_7 string
log_archive_dest_8 string
log_archive_dest_9 string
指定目录位置即可用,但是这样很不利于管理。
简介下SCN:System change number | System Commit Number 但是很多情况下理解成第一种更为准确。

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