fast recovery area
First of all, the version of my enviroment is Oracle 11.0.2.3.
The fast recovery area used to be called flashback recovery area. When you want to enable flashback database feature, your database must have this area. So I always confused about these two concept.
Let`s review how to enable flashback recovery area quickly.
1. Make sure the log mode is archive
select log_mode from v$database;
2. Set the fast recovery area / flashback recovery area
SQL> alter system set db_recovery_file_dest='/flash_recovery_area';
SQL> alter system set db_recovery_file_dest_size=8G;
3. set the flashback retention target
This is controlled by the DB_FLASHBACK_RETENTION_TARGET instance parameter, which is in minutes, and the default is one day. The flashback log space is reused in a circular fashion, older data being overwritten by newer data. This parameter instructs Oracle to keep flashback data for a certain number of minutes before overwriting it:
SQL> alter system set db_flashback_retention_target=240;
It is only a target (four hours in the preceding example) and if the flash recovery area is undersized, Oracle may not be able to keep to it. But in principle, you should be able to flash back to any time within this target.
4. Enable flashback on
SQL> shutdown immediate;
SQL> startup mount;
SQL> alter database flashback on;
SQL> alter database open;
The purpose of this review is to tell you one of funcitons of the fast/flashback recovery area. Then why oracle changed the name of this area from flashback area to fast recovery area? It is because this area have more functions than flashback. Called flashback recovery area may mislead people that this area is used for flashback database only. Actually there are more files can be and should be placed in this area.
From now on we will call it Fast recovery area. The fast recovery area is a default location for all recovery-related files. The fast recovery area can be located in either a file system directory (Oracle will create its own subdirectories within this) or an ASM disk group. The flash recovery area can only be a disk destination. The flash recovery area is not enabled by default, unless the database is created with the Database Configuration Assistant (DBCA).
Files can be stored in the fast recovery area are either permanent or transient. Permanent files are :
- control file mulitplexed copies
- online redo log file mulitplexed copies
If the fast recovery area is defiened during the db creation time. And the control_files parameter , db_create_file_dest parameter not set, then control file copy will be created automatically in the flashback recovery area. Simailarly, if the db_create_online_log_dest_n are not set and you didnt specify where to create the online redo log. The online redo will be created here.
The transient occupants of the flash recovery area are:
- archived redo log files
- rman backups
- rman copies
- control file auto-backups
- flashback log files( in 10g this area is mainly for flashback log files. So we call this area flashback recovery area)
The transient occupants can be deleted automatically by the RMAN Recovery Manager if the flash recovery area is full, if space is needed for more recent transient files, and if the policies in effect permit this.
In previeous 11g release. If none of the LOG_ARCHIVE_DEST_n parameters have been set, then transitioning the database to archivelog mode will internally set LOG_ARCHIVE_DEST_10 to the flash recovery area, if it has been configured. But we know that log_archive_dest and log_archive_dest_n is incompatible. So if you configured the fast recovery area you can not set the log_archive_dest. Or you will hit the error below.
SQL> alter system set log_archive_dest='/oracle_asm/OrclArchiveLog' scope=both;
alter system set log_archive_dest='/oracle_asm/OrclArchiveLog' scope=both
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16018: cannot use LOG_ARCHIVE_DEST with LOG_ARCHIVE_DEST_n or
DB_RECOVERY_FILE_DEST
In 11.0.2.3 the log_arechive_dest_10 will not be set as the db_recovery_file_dest. But you still can not set the log_arch_dest and db_recovery_file_dest at the same time.
If you want to know what kind of files are stored in the fast recovery area you can check the view v$flash_recovery_area_usage.
SQL> select * from v$flash_recovery_area_usage; FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES
-------------------- ------------------ ------------------------- ---------------
CONTROL FILE 0 0 0
REDO LOG 0 0 0
ARCHIVED LOG 2.78 0 8
BACKUP PIECE 0 0 0
IMAGE COPY 0 0 0
FLASHBACK LOG 0 0 0
FOREIGN ARCHIVED LOG 0 0 0
2.78 here means 2.78%.
fast recovery area的更多相关文章
- Flash Recovery Area 的备份
Flash Recovery Area 的备份 备份命令是Flash recovery Area,该命令是Oracle 10g以后才有的.10g引进了flash recovery area,同时在rm ...
- Oracle 释放flash recovery area的四种方法
早上收到一台Linux服务器磁盘告警邮件以及监控告警日志程序发来的邮件.检查过后,发现Linux服务器中一个分区没有空间了.主要原因是由于昨晚程序员做升级时,产生了大量的归档日志,导致联机重做日志无法 ...
- Refresh recovery area usage data after manually deleting files under recovery area
Original source: http://www.dba-oracle.com/t_v$_flash_recovery_area.htm If you manually delete files ...
- Flashback Recovery Area的设置与取消
在Oracle 10g中, Flash back家族分为以下成员: Flashback Database, Flashback Drop,Flashback Query(分Flashback Quer ...
- oracle之Flash Recovery Area全面介绍 (转载)
1. 设置闪回恢复区闪回恢复区主要通过3个初始化参数来设置和管理 db_recovery_file_dest:指定闪回恢复区的位置db_recovery_file_dest_size:指定闪回恢复区的 ...
- Flash Recovery Area空间不足导致DB不能打开或hang住处理方法
当归档目录设置在闪回恢复区,并且闪回恢复区又满了的情况下, DB 就会无法归档而hang住或者无法打开. 这种情况下打开数据库会遇到如下错误信息: SQL> select status from ...
- Flash Recovery Area
1. 设置闪回恢复区 闪回恢复区主要通过3个初始化参数来设置和管理 db_recovery_file_dest:指定闪回恢复区的位置db_recovery_file_dest_size:指定闪回恢复区 ...
- flash recovery area配置
检查数据库是否开启闪回: SQL> select flashback_on from v$database; FLASHBACK_ON ----------------------------- ...
- Oracle的FRA(Flash Recovery Area)的好处
如果FRA的空间耗尽,只会影响到这个Oracle实例自身.所以不会耗尽所有磁盘空间从而影响到其它的数据库实例或其它应用.
随机推荐
- JS数组、数组和学生对象
<html> <head> <meta charset="utf-8"> <title>JS</title> </ ...
- EntityFramework(转自wiki)
维基百科 Entity Framework (又称ADO.NET Entity Framework) 是微软以 ADO.NET 为基础所发展出来的对象关系对应 (O/R Mapping)解决方案,早期 ...
- [ NOI 2001 ] 方程的解数
\(\\\) \(Description\) 已知一个 \(N\) 元高次方程: \[ k_1x_1^{p_1}+k_2x_2^{p_2}+...+k_nx_n^{p_n}=0 \] 要求所有的 \( ...
- Angular——自定义过滤器
基本介绍 除了使用AngularJS内建过滤器外,还可以根业务需要自定义过滤器,通过模块对象实例提供的filter方法自定义过滤器. 基本使用 (1)input是将绑定的数据以参数的形式传入 (2)i ...
- npm换淘宝源 yarn换淘宝源
查询初始的源 npm get registry > https://registry.npmjs.org/ 设置淘宝源 npm config set registry http://regist ...
- HDU_3591_(多重背包+完全背包)
The trouble of Xiaoqian Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/ ...
- nginx做反向代理配置文件的例子
worker_processes ; error_log logs/error.log; #error_log logs/error.log notice; #error_log logs/error ...
- scala学习(2)---option空值处理
https://blog.csdn.net/shadowsama/article/details/78148919 https://www.cnblogs.com/mustone/p/5648914. ...
- css--小白入门篇2
一.css基础选择器 html负责结构,css负责样式,js负责行为. css写在head标签里面,容器style标签. 先写选择器,然后写大括号,大括号里面是样式. 1 <style type ...
- UVA - 11175 From D to E and Back(思路)
题目: 思路: 如图E:图中a.b.c.d是有向图D中的顶点,如果ac.bc都指向cd,而ac又指向ce,那bc同样应该有一条指向ce的边不然就不能从图D转换来.所以直接枚举顶点就可以了. 代码: # ...