h/1_5_673797803.dbf 18-DEC-08
/ora10g/arch/1_6_673797803.dbf 18-DEC-08
/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_6_4no8xl3j_.arc 18-DEC-08
/ora10g/arch/1_7_673797803.dbf 18-DEC-08
/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_7_4no8y3qy_.arc 18-DEC-08
/ora10g/arch/1_8_673797803.dbf 18-DEC-08
NAME COMPLETIO
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/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_8_4no8ys0k_.arc 18-DEC-08
/ora10g/arch/1_9_673797803.dbf 18-DEC-08
/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_9_4no8zdk2_.arc 18-DEC-08
/ora10g/arch/1_10_673797803.dbf 18-DEC-08
/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_10_4no8zfjg_.arc 18-DEC-08
/ora10g/arch/1_11_673797803.dbf 18-DEC-08
/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_11_4no8zg7s_.arc 18-DEC-08
/ora10g/arch/1_12_673797803.dbf 18-DEC-08
/ora10g/flash_recovery_area/EBANK/archivelog/2008_12_18/o1_mf_1_12_4no8zl4s_.arc 18-DEC-08
20 rows selected.
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DB_RECOVERY_FILE_DEST参数是默认的flash recovery area的路径，里面存放有归档日志、闪回日志以及rman的备份文件等文件。
LOG_ARCHIVE_DEST_n参数是存放归档日志的路径，n表示1~10的一个整数，由于归档日志在recovery的时候担当了重要的角色，所以我们可以设置多个归档目录（最多可以设置10个）。这种情况下，联机日志在归档时，会在不同的目录下都会生成有一个相同的归档文件，通过冗余的来保证归档日志的安全。
系统默认的情况是以DB_RECOVERY_FILE_DEST定义的目录来存放归档日志。但是，课上演示的时候，老师已经设置了log_archive_dest_1、log_archive_dest_2和log_archive_dest_3，三个参数。我现在将这三个参数修改回去，让系统使用默认的DB_RECOVERY_FILE_DEST目录来存放归档日志。
经过下面的操作，发现提示找不到归档的目录。
SQL> alter system set log_archive_dest_1='';
SQL> alter system set log_archive_dest_2='';
SQL> alter system set log_archive_dest_3='';
SQL> alter system archive log current;
alter system archive log current
*
ERROR at line 1:
ORA-16014: log 2 sequence# 50 not archived, no available destinations
ORA-00312: online log 2 thread 1: '/opt/ora10g/oradata/orcl/redo02.log'
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /dbs/arch
Oldest online log sequence 49
Next log sequence to archive 50
Current log se