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RMAN – 3 : The DB_UNIQUE_NAME in Backups to the FRA

When you run RMAN Backups to the FRA without using the FORMAT clause, Oracle automatically generates filenames for the BackupPieces. The folder name is derived from the system date. But what is the parent folder for backups ? Is it simply the DB_RECOVERY_FILE_DEST ? Actuallly, the DB_UNIQUE_NAME comes into play as well.

For example :

[oracle@localhost ~]$ rman target /

Recovery Manager: Release 11.2.0.2.0 - Production on Tue Jun 23 16:57:19 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.

connected to target database: ORCL (DBID=1229390655)

RMAN> list backup of datafile 1;

using target database control file instead of recovery catalog

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


BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
1 Full 831.23M DISK 00:03:32 07-JUN-15
BP Key: 1 Status: AVAILABLE Compressed: YES Tag: TAG20150607T165914
Piece Name: /NEW_FS/oracle/FRA/ORCL/backupset/2015_06_07/o1_mf_nnndf_TAG20150607T165914_bq81z2y6_.bkp
List of Datafiles in backup set 1
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 14068320 07-JUN-15 /home/oracle/app/oracle/oradata/orcl/system01.dbf

BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
3 Full 366.89M DISK 00:01:56 07-JUN-15
BP Key: 3 Status: AVAILABLE Compressed: YES Tag: TAG20150607T170754
Piece Name: /NEW_FS/oracle/FRA/ORCL/backupset/2015_06_07/o1_mf_nnndf_TAG20150607T170754_bq82hc5f_.bkp
List of Datafiles in backup set 3
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 14068721 07-JUN-15 /home/oracle/app/oracle/oradata/orcl/system01.dbf

RMAN>

[oracle@localhost ~]$ sqlplus '/ as sysdba'

SQL*Plus: Release 11.2.0.2.0 Production on Tue Jun 23 16:58:34 2015

Copyright (c) 1982, 2010, Oracle. All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> show parameter db_recovery_file_dest

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string /NEW_FS/oracle/FRA
db_recovery_file_dest_size big integer 8G
SQL>

We can see that the DB_RECOVERY_FILE_DEST is defined as “/NEW_FS/oracle/FRA”. However, the backups go into a “backupset” folder under “/NEW_FS/oracle/FRA/ORCL/”. The “ORCL” is part of the path to the folder holding the backups. How is this “ORCL” derived ?

SQL> show parameter db_name

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_name string orcl
SQL> show parameter db_unique_name

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_unique_name string orcl
SQL>

By default, the DB_UNIQUE_NAME is the same as DB_NAME. Let’s see what happens after I change the DB_UNIQUE_NAME.

SQL> 
SQL> !ls -l /NEW_FS/oracle/FRA/
total 4
drwxrwx--- 5 oracle oracle 4096 Jun 7 17:10 ORCL

SQL>
SQL> alter system set db_unique_name='HEMANTDB' scope=SPFILE;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 456146944 bytes
Fixed Size 1344840 bytes
Variable Size 385878712 bytes
Database Buffers 62914560 bytes
Redo Buffers 6008832 bytes
Database mounted.
Database opened.
SQL> !ls -l /NEW_FS/oracle/FRA/
total 4
drwxrwx--- 5 oracle oracle 4096 Jun 7 17:10 ORCL

SQL>

After resetting the DB_UNIQUE_NAME, Oracle doesn’t immediately create the folder for the new DB_UNIQUE_NAME until and unless I run an RMAN Backup.

RMAN> exit

RMAN-06900: WARNING: unable to generate V$RMAN_STATUS or V$RMAN_OUTPUT row
RMAN-06901: WARNING: disabling update of the V$RMAN_STATUS and V$RMAN_OUTPUT rows
ORACLE error from target database:
ORA-03135: connection lost contact
Process ID: 3344
Session ID: 67 Serial number: 13


Recovery Manager complete.
[oracle@localhost ~]$ rman target /

Recovery Manager: Release 11.2.0.2.0 - Production on Tue Jun 23 17:07:14 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.

connected to target database: ORCL (DBID=1229390655)

RMAN> backup datafile 1;

Starting backup at 23-JUN-15
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=27 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=38 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/home/oracle/app/oracle/oradata/orcl/system01.dbf
channel ORA_DISK_1: starting piece 1 at 23-JUN-15
channel ORA_DISK_1: finished piece 1 at 23-JUN-15
piece handle=/NEW_FS/oracle/FRA/HEMANTDB/backupset/2015_06_23/o1_mf_nnndf_TAG20150623T170721_brl8g9od_.bkp tag=TAG20150623T170721 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:25
Finished backup at 23-JUN-15

Starting Control File and SPFILE Autobackup at 23-JUN-15
piece handle=/NEW_FS/oracle/FRA/HEMANTDB/autobackup/2015_06_23/o1_mf_s_883156126_brl8k0w4_.bkp comment=NONE
Finished Control File and SPFILE Autobackup at 23-JUN-15

RMAN>

SQL> !ls -l /NEW_FS/oracle/FRA/
total 8
drwxrwx--- 3 oracle oracle 4096 Jun 23 17:07 HEMANTDB
drwxrwx--- 5 oracle oracle 4096 Jun 7 17:10 ORCL

SQL>
SQL> show parameter db_name

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_name string orcl
SQL> show parameter db_unique_name

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_unique_name string HEMANTDB
SQL>

Notice how Oracle created the “HEMANTDB” folder under the designated DB_RECOVERY_FILE_DEST. It then created the “backupset” and “autobackup” folders also as subfolders under this. BackupSet BackupPieces and Controlfile Autobackups are now going to the new path. The backups are go to folders under {DB_RECOVERY_FILE_DEST}/{DB_UNIQUE_NAME}
.
.
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