业务增长发展迅猛，归档日志增长太快，磁盘承受不了，所以准备做个定时清理归档日志的定时任务
ORACLE 定时清理归档日志详细过程
1、RM方式清理归档日志
清理归档日志，可以人为的删除已经归档好的日志文件，然后再调用rman里面RMAN> crosscheck archivelog all;来去数据库里面删除归档记录；也可以通过ram调用delete命令来删除归档日志。
2、使用rman清理归档日志
RMAN清除方式会自动清除磁盘上的归档日志文件，同时会释放控制文件中对应的归档日志的归档信息。
可以基于不同的条件来清除归档日志，如基于SCN，基于SEQUENCE，基于TIME等方式。
对于上述的三种方式又可以配合from, until, between .. and .. 等等子句来限定范围，方式灵活多变。
下面的命令用于校验归档日志的有效性，列出无效的归档日志，以及以何种方式清除归档日志，列出几种常用的:
delete noprompt archivelog until time "to_date('XXXX-XX-XX','YYYY-MM-DD')"; ---> 清理到某天日期之前的归档
delete noprompt archivelog until time "to_date('2016-09-14 18:00:00','YYYY-MM-DD hh24:mi:ss')"; ---> 清理到具体时分秒之前的归档日志
cross check archivelog all; --->校验日志的可用性
list expired archivelog all; --->列出所有失效的归档日志
delete archivelog until sequence 16; --->删除log sequence为16及16之前的所有归档日志
delete archivelog all completed before 'sysdate-7'; --->删除系统时间7天以前的归档日志，不会删除闪回区有效的归档日志
delete archivelog all completed before 'sysdate - 1'; --->同上，1天以前的
delete archivelog from time 'sysdate-1'; --->注意这个命令，删除系统时间1天以内到现在的归档日志
delete noprompt archivelog all completed before 'sysdate'; --->该命令清除当前所有的归档日志
delete noprompt archivelog all completed before 'sysdate-0'; --->该命令清除当前所有的归档日志
delete noprompt archivelog all; --->同上一命令
3、实现清理一个小时前的归档日志
执行命令：delete force archivelog all completed before 'sysdate-1/24';
（1）查看当前时间
[oracle@hch_test_121_90 ~]$ date
Tue Oct 11 11:20:20 CST 2016
[oracle@hch_test_121_90 ~]$
（2）查看当前一个小时之前的归档日志，看到有一个o1_mf_1_2822_czrm1dj8_.arc，如下所示：
[oracle@hch_test_121_90 ~]$ ll /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/ |more
total 3181880
-rw-r----- 1 oracle oinstall 41340416 Oct 11 10:19 o1_mf_1_2822_czrm1dj8_.arc
-rw-r----- 1 oracle oinstall 40434176 Oct 11 10:20 o1_mf_1_2823_czrm49l9_.arc
-rw-r----- 1 oracle oinstall 41180160 Oct 11 10:22 o1_mf_1_2824_czrm76nd_.arc
-rw-r----- 1 oracle oinstall 40340480 Oct 11 10:23 o1_mf_1_2825_czrm9xos_.arc
（3）开始执行删除命令，按计划删除这一条归档日志
RMAN> delete force archivelog all completed before 'sysdate-1/24';
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=11 device type=DISK
List of Archived Log Copies for database with db_unique_name POWERDES
=====================================================================
Key Thrd Seq S Low Time
------- ---- ------- - ---------
1396 1 2822 A 11-OCT-16
Name: /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2822_czrm1dj8_.arc
Do you really want to delete the above objects (enter YES or NO)? YES # 输入删除命令
deleted archived log
archived log file name=/oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2822_czrm1dj8_.arc RECID=1396 STAMP=924949164
Deleted 1 objects
RMAN>
4、自动化脚本定时任务实现清理一个小时前的归档日志
（1）自动化脚本
[root@hch_test_121_90 ~]# more archivelog_clear.sh
#!/bin/sh
BACK_DIR=/oracle/clear_archlog/data
export DATE=`date +%F`
echo " " >> $BACK_DIR/$DATE/rman_backup.log
echo `date '+%Y-%m-%d %H:%M:%S'` >> $BACK_DIR/$DATE/rman_backup.log
su - oracle -c "
mkdir -p $BACK_DIR/$DATE
rman log=$BACK_DIR/$DATE/rman_backup.log target / <<EOF
# delete force archivelog all completed before 'sysdate-1/24'; # 这里执行清除归档日志，如果不想手动输入YES，则可以添加noprompt参数
delete force noprompt archivelog all completed before 'sysdate-1/24';
exit;
EOF
"
echo " " >> $BACK_DIR/$DATE/rman_backup.log
（2）crontab定时任务
[root@hch_test_121_90 ~]# crontab -l
10 */1 * * * sh /home/oracle/archivelog_clear.sh
（3）查看执行后的日志
[root@hch_test_121_90 ~]# more /oracle/clear_archlog/data/2016-10-11/rman_backup.log
Recovery Manager: Release 11.2.0.1.0 - Production on Tue Oct 11 11:28:04 2016
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
connected to target database: POWERDES (DBID=3458668465)
RMAN>
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=137 device type=DISK
List of Archived Log Copies for database with db_unique_name POWERDES
=====================================================================
Key Thrd Seq S Low Time
------- ---- ------- - ---------
1397 1 2823 A 11-OCT-16
Name: /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2823_czrm49l9_.arc
1398 1 2824 A 11-OCT-16
Name: /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2824_czrm76nd_.arc
1399 1 2825 A 11-OCT-16
Name: /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2825_czrm9xos_.arc
1400 1 2826 A 11-OCT-16
Name: /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2826_czrmdqqy_.arc
1401 1 2827 A 11-OCT-16
Name: /oracle/app/oracle/flash_recovery_area/POWERDES/archivelog/2016_10_11/o1_mf_1_2827_czrmhksn_.arc
Do you really want to delete the above objects (enter YES or NO)? "exit;" is an invalid response - please re-enter.
Do you really want to delete the above objects (enter YES or NO)?
Error occurred getting response - assuming NO response
RMAN>
Recovery Manager complete.
