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Compression — 4 : RMAN (BASIC) Compression

BASIC Compression in RMAN is free with the Enterprise Edition. Advanced Compression with a specified algorithm requires the Advanced Compression Option Licence.

RMAN> backup as compressed backupset database root;

Starting backup at 19-MAR-16
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=48 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=00003 name=/u01/app/oracle/oradata/ORCL/datafile/o1_mf_sysaux_9fxmvhl3_.dbf
input datafile file number=00001 name=/u01/app/oracle/oradata/ORCL/datafile/o1_mf_system_9fxmx6s1_.dbf
input datafile file number=00004 name=/u01/app/oracle/oradata/ORCL/datafile/o1_mf_undotbs1_9fxn0vgg_.dbf
input datafile file number=00006 name=/u01/app/oracle/oradata/ORCL/datafile/o1_mf_users_9fxn0t8s_.dbf
channel ORA_DISK_1: starting piece 1 at 19-MAR-16
channel ORA_DISK_1: finished piece 1 at 19-MAR-16
piece handle=/u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T081217_cgtjk2ms_.bkp tag=TAG20160319T081217 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:02:16
Finished backup at 19-MAR-16

Starting Control File and SPFILE Autobackup at 19-MAR-16
piece handle=/u01/app/oracle/fast_recovery_area/ORCL/autobackup/2016_03_19/o1_mf_s_906884075_cgtjofh1_.bkp comment=NONE
Finished Control File and SPFILE Autobackup at 19-MAR-16

RMAN> list backup;


List of Backup Sets
===================


BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
1 Full 385.78M DISK 00:02:09 19-MAR-16
BP Key: 1 Status: AVAILABLE Compressed: YES Tag: TAG20160319T081217
Piece Name: /u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T081217_cgtjk2ms_.bkp
List of Datafiles in backup set 1
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 3034354 19-MAR-16 /u01/app/oracle/oradata/ORCL/datafile/o1_mf_system_9fxmx6s1_.dbf
3 Full 3034354 19-MAR-16 /u01/app/oracle/oradata/ORCL/datafile/o1_mf_sysaux_9fxmvhl3_.dbf
4 Full 3034354 19-MAR-16 /u01/app/oracle/oradata/ORCL/datafile/o1_mf_undotbs1_9fxn0vgg_.dbf
6 Full 3034354 19-MAR-16 /u01/app/oracle/oradata/ORCL/datafile/o1_mf_users_9fxn0t8s_.dbf

BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
2 Full 17.20M DISK 00:00:03 19-MAR-16
BP Key: 2 Status: AVAILABLE Compressed: NO Tag: TAG20160319T081435
Piece Name: /u01/app/oracle/fast_recovery_area/ORCL/autobackup/2016_03_19/o1_mf_s_906884075_cgtjofh1_.bkp
SPFILE Included: Modification time: 19-MAR-16
SPFILE db_unique_name: ORCL
Control File Included: Ckp SCN: 3034519 Ckp time: 19-MAR-16

RMAN>
CDB$ROOT@ORCL> l
1 select status, command_id, to_char(start_time,'DD-MON HH24:MI') Start_At, to_char(end_time,'DD-MON HH24:MI') End_At,
2 trunc(input_bytes/1048576) Input_MB, trunc(output_bytes/1048576) Output_MB, input_type
3 from v$rman_backup_job_details
4* order by start_time
CDB$ROOT@ORCL>
CDB$ROOT@ORCL> /

STATUS COMMAND_ID START_AT END_AT INPUT_MB OUTPUT_MB
------------------- ------------------------- ----------------- ------------- ---------- ----------
INPUT_TYPE
-------------
COMPLETED 2016-03-19T08:12:02 19-MAR 08:12 19-MAR 08:14 1807 402
DB FULL


CDB$ROOT@ORCL>

Compare the INPUT_MB and OUTPUT_MB to see the compression achieved.

Default compression can also be configured with

RMAN> show compression algorithm;

RMAN configuration parameters for database with db_unique_name ORCL are:
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default

RMAN>
RMAN> CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET;

new RMAN configuration parameters:
CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET PARALLELISM 1;
new RMAN configuration parameters are successfully stored

RMAN>
RMAN> backup datafile 1;

Starting backup at 19-MAR-16
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=1 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/ORCL/datafile/o1_mf_system_9fxmx6s1_.dbf
channel ORA_DISK_1: starting piece 1 at 19-MAR-16
channel ORA_DISK_1: finished piece 1 at 19-MAR-16
piece handle=/u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T082704_cgtkdrdh_.bkp tag=TAG20160319T082704 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:55
Finished backup at 19-MAR-16

Starting Control File and SPFILE Autobackup at 19-MAR-16
piece handle=/u01/app/oracle/fast_recovery_area/ORCL/autobackup/2016_03_19/o1_mf_s_906884879_cgtkgk5d_.bkp comment=NONE
Finished Control File and SPFILE Autobackup at 19-MAR-16

RMAN> list backup of datafile 1;


List of Backup Sets
===================


BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
1 Full 385.78M DISK 00:02:09 19-MAR-16
BP Key: 1 Status: AVAILABLE Compressed: YES Tag: TAG20160319T081217
Piece Name: /u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T081217_cgtjk2ms_.bkp
List of Datafiles in backup set 1
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 3034354 19-MAR-16 /u01/app/oracle/oradata/ORCL/datafile/o1_mf_system_9fxmx6s1_.dbf

BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
3 Full 207.82M DISK 00:00:55 19-MAR-16
BP Key: 3 Status: AVAILABLE Compressed: YES Tag: TAG20160319T082704
Piece Name: /u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T082704_cgtkdrdh_.bkp
List of Datafiles in backup set 3
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 3035302 19-MAR-16 /u01/app/oracle/oradata/ORCL/datafile/o1_mf_system_9fxmx6s1_.dbf

RMAN>
CDB$ROOT@ORCL> l
1 select status, command_id, to_char(start_time,'DD-MON HH24:MI') Start_At, to_char(end_time,'DD-MON HH24:MI') End_At,
2 trunc(input_bytes/1048576) Input_MB, trunc(output_bytes/1048576) Output_MB, input_type
3 from v$rman_backup_job_details
4* order by start_time
CDB$ROOT@ORCL> /

STATUS COMMAND_ID START_AT END_AT INPUT_MB OUTPUT_MB
------------------- ------------------------- ----------------- ----------------- --------- ---------
INPUT_TYPE
-------------
COMPLETED 2016-03-19T08:12:02 19-MAR 08:12 19-MAR 08:14 1807 402
DB FULL

COMPLETED 2016-03-19T08:18:29 19-MAR 08:27 19-MAR 08:28 803 225
DATAFILE FULL


CDB$ROOT@ORCL>
CDB$ROOT@ORCL> !du -sh /u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T082704_cgtkdrdh_.bkp
208M /u01/app/oracle/fast_recovery_area/ORCL/backupset/2016_03_19/o1_mf_nnndf_TAG20160319T082704_cgtkdrdh_.bkp

CDB$ROOT@ORCL>

Note the slight discrepancy in reported backuppiece size. The LIST BACKUP shows it as 207.82MB, the query on v$rman_backup_job_details dividing the output_bytes by 1048576 shows the size as 225MB (truncating to units) while the OS level “du -sh” command shows it as 208MB.
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