小實(shí)驗(yàn)，開啟閃回和關(guān)閉閃回。

12c RAC 閃回環(huán)境
實(shí)際上就是后臺(tái)啟動(dòng)了rvwr這個(gè)進(jìn)程，然后自動(dòng)創(chuàng)建了一個(gè)flashback目錄，然后寫入閃回日志而已。當(dāng)我們臨時(shí)想清理閃回日志，只要關(guān)閉閃回就可以了，系統(tǒng)會(huì)自動(dòng)delete閃回日志的。

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SYS@orcl1> alter database flashback off;

Database altered.

看日志

2018-01-06 09:46:54.618000 +08:00
RVWR shutting down  --關(guān)閉進(jìn)程
Deleted Oracle managed file +DATADG/ORCL/FLASHBACK/log_1.355.964691155
Deleted Oracle managed file +DATADG/ORCL/FLASHBACK/log_2.357.964691159
Flashback Database Disabled 
Completed: alter database flashback off

看asm目錄

ASMCMD [+datadg/orcl/flashback] > ls
log_1.355.964691155
log_2.357.964691159
ASMCMD [+datadg/orcl/flashback] > ls
ASMCMD-8002: entry 'flashback' does not exist in directory '+datadg/orcl/'
ASMCMD [+datadg/orcl/flashback] >

啟動(dòng)閃回

SYS@orcl1> alter database flashback on;

Database altered.

SYS@orcl1> 

看日志，實(shí)際是后天進(jìn)程啟動(dòng)RVWR

alter database flashback on
Starting background process RVWR
RVWR started with pid=33, OS id=17582  --啟動(dòng)進(jìn)程
2018-01-06 09:51:26.483000 +08:00
Flashback Database Enabled at SCN 11549479
Completed: alter database flashback on

asm自動(dòng)創(chuàng)建目錄

ASMCMD [+datadg/orcl/flashback] > ls -l
Type       Redund  Striped  Time             Sys  Name
FLASHBACK  UNPROT  COARSE   JAN 06 09:00:00  Y    log_1.357.964691481
FLASHBACK  UNPROT  COARSE   JAN 06 09:00:00  Y    log_2.355.964691483
ASMCMD [+datadg/orcl/flashback] >