答案选D
A是设置备份集大小
B是设置并行度
C是设置保留策略
答案D
RMAN can duplex backups to either disk or tape, but cannot duplex backups to tape and disk simultaneously. When backing up to tape, ensure that the number of copies does not exceed the number of available tape devices. The following examples show possible duplexing configurations:
# Makes 2 disk copies of each datafile and control file backup set
# (autobackups excluded)
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2;
# Makes 3 copies of every archived redo log backup to tape
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE sbt TO 3;
http://docs.oracle.com/cd/E25054 ... mconfa.htm#BRADV139
