delete noprompt archivelog

删除7天前已经备份的归档日志

delete noprompt archivelog all completed before 'sysdate - 7';

备份没有备份的归档日志

backup archivelog all not backed up;

不备份已经备份1次的归档日志

backup archivelog all not backed up 1 times;　　

归档日志备份过两次的， 第三次是不进行备份的

backup archivelog all not backed up 2 times;　

crosscheck archivelog all;
delete noprompt archivelog all completed before 'sysdate - 1/2' BACKED UP 1 TIMES TO DEVICE TYPE SBT;

delete noprompt archivelog all backed up 1 times to DEVICE TYPE SBT completed before 'sysdate-1/2';

backup archivelog all not backed up 1 times;　　---- # 不备份上次已经备份的归档
crosscheck archivelog all;
resync catalog;