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关于Flashback日志管理的文档参考

原创 Linux操作系统 作者:todayboy 时间:2012-02-17 13:43:49 0 删除 编辑

关于Flashback日志管理的文档参考

 

This document is being delivered to you via Oracle Support\'s Rapid Visibility (RaV) process, and therefore has not been subject to an independent technical review.

Applies to:
Oracle Server Enterprise Edition - Version: 10.1.0.2 to 10.2.0.1
Information in this document applies to any platform.
Oracle Server - Enterprise Edition - Version: 10.1.0.2 to 10.2.0.1
Goal
The  recovery file dest is full of flashback logs. There are ORA-19815 errors in the production alert log, then its necessary to remove or reuse the flashback logs (FBL).

Solution
Flashback logs are handled internally and we have no control over them. This means
that we cannot delete flashback logs manually, the ONLY way to delete then
is disabling FLASHBACK.

The FlashBack Logs can ONLY be deleted by DISABLING FLASHBACK
on database level

SQL> startup mount
     alter database flashback off;
     alter database open;

During space pressure, the Flashback logs are deleted under two
conditions:

1) When an archivelog is deleted, it would also delete the flashback logs
    that are dependent on the archived log.
2) When quota is shrunk, then flashback logs is deleted to reclaim disk
    space. This is decreasing the DB_RECOVERY_FILE_DEST_SIZE to such a value
     that the  FLB itself will run into a space pressure and than the old
     FLB\'s will get  deleted.

We can hit bellow bug and then the flashback logs are not deleted
even there is space pressure in the Flash backup disk space.   
   

Bug 5106952
Hdr: 5106952 10.2.0.1.0 RDBMS 10.2.0.1.0 FLASHBACK_DB PRODID-5 PORTID-23
Abstract: FLASHBACK LOG SPACE NOT BEING RECLAIMED
Fixed In Ver: 11.0
Also the bug is  fixed in patch set 10.1.0.6  and 10.2.0.3 .


The workaround to this  bugs is to disable flashback database option then it  will  be possible to remove the FBL.

1.- First of all we need to check if there is any guaranteed restore point defined:

select name,scn,time,database_incarnation#,guarantee_flashback_database,storage_size from v$restore_point;


2.- Remove all the restore points

     Drop restore point ;

  3.- Check how much space is used before turning off Flashback

    select * from v$flash_recovery_area_usage;

4.- ALTER DATABASE FLASHBACK OFF;


5.-  Now you can delete the Flashback logs manually


6.- ALTER DATABASE FLASHBACK ON;


7.- Check that there are no flashback logs before turning back on

       select * from v$flash_recovery_area_usage;

 

总结:故障原因未明,不知道是不是Bug?

看来oracle 自己可以管理Flash日志文件,一般不需要手动删除

 

 

source:http://blog.sina.com.cn/s/blog_48e13c9e0100gvjg.html

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