RMAN Cross Platform Tablespace Transport Over Network
12.1 introduced cross platform data transport using backup-sets. We could perform database/tablespace backups using FOR TRANSPORT / TO PLATFORM clause and restore the same to a different OS Platform. This typically involved 3 steps: create backup on source, copy backup-piece to destination and perform restoration on destination.
Starting from 12.2, we can perform cross platform transport of datafiles directly over the network using the FROM SERVICE clause along with the RESTORE FOREIGN DATAFILE command. This command internally performs a cross platform backup of the requested datafiles on source, the backup-piece chunks are transferred to destination over network and restoration is performed on destination.
SOLUTION
Below steps demonstrate a cross platform transport of tablespace EXAMPLE from source platform AIX (Big Endian) to destination Linux (Little Endian)
1. On source, check the datafiles which belong to tablespace EXAMPLE
SQL> select FILE_ID from DBA_DATA_FILES where TABLESPACE_NAME=’EXAMPLE’;
FILE_ID
———-
2
2. On destination, perform a cross platform restore of datafiles belonging to source tablespace EXAMPLE using FROM SERVICE clause:
Note: Start RMAN and connect to the destination database (not the source database) as TARGET.
rman target sys/<password>@<destination_tns>
RMAN> restore foreign datafile 2
2> format ‘/<destination_path>/example01.dbf’
3> from service <source_service_name>;
We can perform the migration using consistent or inconsistent backups. If using consistent backup, put the tablespace EXAMPLE in READ ONLY mode before running above restore command. If using inconsistent backups, the tablespace can remain in READ WRITE mode while performing initial restore.
3. If above restoration was done with tablespace in READ ONLY mode, then recovery is not required. You can skip to next step i.e. step# 4. However, if restoration was done with tablespace in READ WRITE mode, then we need to perform recovery. This can also be done directly over the network. Multiple recovery attempts can be performed while the source tablespace is in READ WRITE mode to sync it with latest changes being done on source.
Start RMAN and connect to the destination database (not the source database) as TARGET and execute RMAN recover command.
rman target sys/<password>@<destination_tns>
RMAN> recover foreign datafilecopy ‘/<destination_path>/example01.dbf’
2> from service <source_service_name>;
Before, performing final recovery, put source tablepace in READ ONLY modeSQL> alter tablespace EXAMPLE read only;
And, perform a final recovery on destination
rman target sys/<password>@<destination_tns>
RMAN> recover foreign datafilecopy ‘/<destination_path>/example01.dbf’
2> from service <source_service_name>;
4. We now have a consistent datafile on destination but it’s not yet plugged into the destination database. For this, we need to perform metadata export on source and metadata import in destination. We can also combine these 2 steps using network_link option of impdp. For this, create a database link in the destination database pointing to source database:SQL> create public database link <dblink> connect to system identified by oracle using ‘<source_service_name>’;
And then, perform the metadata import (user system is used in this example)impdp system/<password> network_link=<dblink> transport_tablespaces=EXAMPLE transport_datafiles=’/<destination_path>/example01.dbf’
