185.A shoot-out has erupted between your MS development teams using .NET and your Linux
development teams using Java. Knowing that your database is in danger, which command would you use
to back up your NOARCHIVELOG mode database using RMAN with compression?
A. backup database all
B. backup compressed database
C. backup as compressed backupset database;
D. backup as compressed backup database plus archivelog all;
E. backup as compressed backupset database plus compress archivelog all;
Answer: C
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmbckba.htm#BRADV8138
在noarchivelog模式下不能备份。
SQL> archive log list
Database log mode No Archive Mode
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 8
Current log sequence 10
SQL> !
[oracle@node2 ~]$ rman target /
Recovery Manager: Release 11.2.0.4.0 - Production on Sun Feb 23 11:45:09 2014
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: TEST0221 (DBID=3883475966)
RMAN> backup as compressed backupset database;
Starting backup at 23-FEB-14
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=33 device type=DISK
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 02/23/2014 11:46:01
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode
continuing other job steps, job failed will not be re-run
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 23-FEB-14
channel ORA_DISK_1: finished piece 1 at 23-FEB-14
piece handle=/u01/app/oracle/fast_recovery_area/TEST0221/backupset/2014_02_23/o1_mf_ncsnf_TAG20140223T114559_9jlvqv10_.bkp tag=TAG20140223T114559 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:04
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 02/23/2014 11:46:01
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode
RMAN>
----------------------------------------------------------------------------------------
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 8
Next log sequence to archive 10
Current log sequence 10
SQL> !
[oracle@node2 ~]$ rman target /
Recovery Manager: Release 11.2.0.4.0 - Production on Sun Feb 23 11:49:43 2014
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: TEST0221 (DBID=3883475966)
RMAN> backup as compressed backupset database;
Starting backup at 23-FEB-14
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=26 device type=DISK
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/u01/app/oracle/oradata/test0221/system01.dbf
input datafile file number=00002 name=/u01/app/oracle/oradata/test0221/sysaux01.dbf
input datafile file number=00005 name=/u01/app/oracle/oradata/test0221/example01.dbf
input datafile file number=00003 name=/u01/app/oracle/oradata/test0221/undotbs01.dbf
input datafile file number=00004 name=/u01/app/oracle/oradata/test0221/users01.dbf
channel ORA_DISK_1: starting piece 1 at 23-FEB-14
channel ORA_DISK_1: finished piece 1 at 23-FEB-14
piece handle=/u01/app/oracle/fast_recovery_area/TEST0221/backupset/2014_02_23/o1_mf_nnndf_TAG20140223T114959_9jlvz90q_.bkp tag=TAG20140223T114959 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:03:36
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 23-FEB-14
channel ORA_DISK_1: finished piece 1 at 23-FEB-14
piece handle=/u01/app/oracle/fast_recovery_area/TEST0221/backupset/2014_02_23/o1_mf_ncsnf_TAG20140223T114959_9jlw64w0_.bkp tag=TAG20140223T114959 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:04
Finished backup at 23-FEB-14
RMAN>
------------------------------------------------------------------------------------
Making Compressed Backups
For any use of the BACKUP command that creates backup
sets, you can take advantage of RMAN support for binary compression of backup sets. Specify
theAS COMPRESSED BACKUPSET option to the BACKUP command.
RMAN compresses the backup set contents before writing them to disk. The details of which binary compression level is used are automatically recorded in the backup set. There is no need to explicitly mention the type of compression used or how to decompress the backup set in the recovery operation.
Example 9-7 backs up the entire database and archived logs to the configured default backup destination (disk or tape), producing compressed backup sets.
Binary compression creates some performance overhead during backup and restore operations. Binary compression consumes CPU resources, so compressed backups should not be scheduled when CPU usage is high. However, the following circumstances may warrant paying the performance penalty:
-
You are using disk-based backups when disk space in your fast recovery area or other disk-based backup destination is limited.
-
You are performing your backups to some device over a network when reduced network bandwidth is more important than CPU usage.
-
You are using some archival backup media such as CD or DVD, where reducing backup sizes saves on media costs and archival storage.