[20161102]CONFIGURE CONTROLFILE AUTOBACKUP ON.txt
--正常情况下,许多dba都建议设置CONFIGURE CONTROLFILE AUTOBACKUP ON,这样在增加删除表空间等数据库维护操作时,做备份时,自动建
--立控制文件与spfile文件的备份.
--许多人也观察到在维护数据库增加数据文件时,并不会马上做控制文件的自动备份,实际上又一些小小延迟.受参数_controlfile_autobackup_delay
--的控制,这样的目地在于如果增加很多数据文件,频繁备份并不是非常必要,适当延迟可以避免频繁备份控制文件.
--做一个小测试:
1.环境:
SYS@book> @ &r/ver1
PORT_STRING VERSION BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
SYS@book> @ &r/hide _controlfile_autobackup_delay
NAME DESCRIPTION DEFAULT_VALUE SESSION_VALUE SYSTEM_VALUE
----------------------------- -------------------------------------------------------------- ------------- ------------- ------------
_controlfile_autobackup_delay time delay (in seconds) for performing controlfile autobackups TRUE 300 300
2.建立表空间看看：
CREATE TABLESPACE TEA DATAFILE
'/mnt/ramdisk/book/tea01.dbf' SIZE 1M AUTOEXTEND ON NEXT 16M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON;
3.观察是否备份控制文件.
RMAN> list backup of controlfile;
specification does not match any backup in the repository
--wait 300秒
RMAN> list backup;
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ -------------------
46 Full 9.52M DISK 00:00:00 2016-11-02 08:49:21
BP Key: 46 Status: AVAILABLE Compressed: NO Tag: TAG20161102T084921
Piece Name: /u01/app/oracle/fast_recovery_area/BOOK/autobackup/2016_11_02/o1_mf_s_926844561_d1lg0k8y_.bkp
SPFILE Included: Modification time: 2016-10-17 08:51:21
SPFILE db_unique_name: BOOK
Control File Included: Ckp SCN: 2450432 Ckp time: 2016-11-02 08:49:21
--看看
Wed Nov 02 08:39:23 2016
CREATE TABLESPACE TEA DATAFILE
'/mnt/ramdisk/book/tea01.dbf' SIZE 1M AUTOEXTEND ON NEXT 16M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON
Completed: CREATE TABLESPACE TEA DATAFILE
'/mnt/ramdisk/book/tea01.dbf' SIZE 1M AUTOEXTEND ON NEXT 16M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON
--可以发现时间还是存在一些差异，实际上是10分钟后才做了备份。
--后台派生进程MMON slave 会跟踪控制文件的建立信息, 一般命令格式: SID__m000_
*** 2016-11-02 08:49:21.246
*** SESSION ID:(68.7) 2016-11-02 08:49:21.246
*** CLIENT ID:() 2016-11-02 08:49:21.246
*** SERVICE NAME:(SYS$BACKGROUND) 2016-11-02 08:49:21.246
*** MODULE NAME:(MMON_SLAVE) 2016-11-02 08:49:21.246
*** ACTION NAME:(Autobackup Control File) 2016-11-02 08:49:21.246
Starting control autobackup
Control autobackup written to DISK device
handle '/u01/app/oracle/fast_recovery_area/BOOK/autobackup/2016_11_02/o1_mf_s_926844561_d1lg0k8y_.bkp'