[每日一题] 11gOCP 1z0-053 :2013-10-15 duplexing of the backups
正确答案DB
这道题目没什么深入的原理，我们从答案入一一分析。
答案A不正确，多路复用可以备份在磁带和磁盘，根据经验答案不能确定是对是错的看到这种还有“only”只有唯一的单词，一般是错的。
答案B正确，镜像拷贝不支持多路径复用，实验加以验证，看下面实验：
[html] RMAN> copy datafile 10 to '/backup/disk1/df10_1','/backup/disk1/df10_2'; RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-00558: error encountered while parsing input commands RMAN-01009: syntax error: found "single-quoted-string": expecting one of: "archivelog, backup, controlfilecopy, current, datafilecopy, datafile" RMAN-01007: at line 1 column 44 file: standard input RMAN> copy datafile 10 to '/backup/disk1/df10_1'; Starting backup at 16-OCT-13 using channel ORA_DISK_1 channel ORA_DISK_1: starting datafile copy input datafile file number=00010 name=/u01/app/oracle/oradata/ocm/tp2.dbf output file name=/backup/disk1/df10_1 tag=TAG20131016T001904 RECID=5 STAMP=828922746 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03 Finished backup at 16-OCT-13 Starting Control File and SPFILE Autobackup at 16-OCT-13 piece handle=/backup/rman/c-2206937749-20131016-01 comment=NONE Finished Control File and SPFILE Autobackup at 16-OCT-13
答案C不正确，并行度与镜像拷数无关，实验加以验证，看下面实验：
[html] RMAN> show all; RMAN configuration parameters for database with db_unique_name OCM are: CONFIGURE RETENTION POLICY TO REDUNDANCY 2; CONFIGURE BACKUP OPTIMIZATION ON; CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default CONFIGURE CONTROLFILE AUTOBACKUP ON; CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/backup/rman/%F'; CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '%U'; CONFIGURE MAXSETSIZE TO UNLIMITED; # default CONFIGURE ENCRYPTION FOR DATABASE OFF; # default CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0/dbs/snapcf_ocm.f'; # default RMAN>CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2; old RMAN configuration parameters: CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; new RMAN configuration parameters: CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2; new RMAN configuration parameters are successfully stored CONFIGUREDEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET;--并行度是1也没关系 CONFIGUREDATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2;--备份集多路径
对10文件多路径备份，这里我们的并行度为1，备份集多径路2，此时并行度与多径路不一样，也可以备份。
[html]
RMAN> report schema;
Report of database schema for database with db_unique_name OCM
List of Permanent Datafiles
===========================
File Size(MB) Tablespace RB segs Datafile Name
---- -------- -------------------- ------- ------------------------
1 730 SYSTEM *** /u01/app/oracle/oradata/ocm