[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/system01.dbf  
2    710      SYSAUX               ***     /u01/app/oracle/oradata/ocm/sysaux01.dbf  
3    110      UNDOTBS1             ***     /u01/app/oracle/oradata/ocm/undotbs01.dbf  
4    5        USERS                ***     /u01/app/oracle/oradata/ocm/users01.dbf  
5    345      EXAMPLE              ***     /u01/app/oracle/oradata/ocm/example01.dbf  
6    100      GYJ                  ***     /u01/app/oracle/oradata/ocm/gyj01.dbf  
7    50       GYJ                  ***     /u01/app/oracle/oradata/ocm/gyj02.dbf  
8    10       TP1                  ***     /u01/app/oracle/oradata/ocm/tp01.dbf  
9    10       MRKT                 ***     /u01/app/oracle/oradata/ocm/mrkt01.dbf  
10   100      TP2                  ***     /u01/app/oracle/oradata/ocm/tp2.dbf  
  
List of Temporary Files  
=======================  
File Size(MB) Tablespace           Maxsize(MB) Tempfile Name  
---- -------- -------------------- ----------- --------------------  
1    20       TEMP                 32767       /u01/app/oracle/oradata/ocm/temp01.dbf  
2    10       TEMP1                10          /u01/app/oracle/oradata/ocm/temp02.dbf  
3    10       TEMP4                10          /u01/app/oracle/oradata/ocm/temp04.dbf  
  
RMAN> backup datafile 10 format '/backup/disk1/%U','/backup/disk2/%U';  
  
Starting backup at 16-OCT-13  
using channel ORA_DISK_1  
channel ORA_DISK_1: starting full datafile backup set  
channel ORA_DISK_1: specifying datafile(s) in backup set  
input datafile file number=00010 name=/u01/app/oracle/oradata/ocm/tp2.dbf  
channel ORA_DISK_1: starting piece 1 at 16-OCT-13  
channel ORA_DISK_1: finished piece 1 at 16-OCT-13 with 2 copies and tag TAG20131016T001426  
piece handle=/backup/disk1/1gomgmj2_1_1 comment=NONE  
piece handle=/backup/disk2/1gomgmj2_1_2 comment=NONE  
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01  
Finished backup at 16-OCT-13  
  
Starting Control File and SPFILE Autobackup at 16-OCT-13  
piece handle=/backup/rman/c-2206937749-20131016-00 comment=NONE  
Finished Control File and SPFILE Autobackup at 16-OCT-13