14 Creating Transportable Tablespace Sets from Backup with RMAN

When to Use RMAN to Create Transportable Tablespace Sets

In any situation where you need transportable tablespaces, you can use the RMAN TRANSPORT TABLESPACE command to create them, as long as you have RMAN backups of your database that can be recovered to the SCN at which you need the tablespaces. Scenarios for using transportable tablespaces are described in Oracle Database Administrator's Guide.

However, there are two specific scenarios in which this feature is particularly useful:

• Creating transportable tablespace sets for use with a tablespace repository. For example, you have a database with some tablespaces used for quarterly reporting. You use TRANSPORT TABLESPACE to create transportable tablespace sets for those tablespaces quarterly for storage in a tablespace repository. Subsequently, versions of the tablespace can be requested from the repository and attached to some other database for use in the reporting process.

  See also:

  Oracle Streams Replication Administrator's Guide for more details on RMAN and tablespace repositories

• When preparing to use Streams to keep a destination database synchronized with a source database, you must perform Streams instantiation, to bring the destination database up to a given SCN at which the two databases were known to be synchronized, before you can actually use Streams to move subsequent updates from the source to the target. Creating the transportable tablespace set from backup can be used as part of the process of Streams instantiation.

  See also:

  Oracle Streams Replication Administrator's Guide for more details on RMAN and Streams instantiation

How RMAN Creates Transportable Tablespace Sets from Backup

The following diagram illustrates the process of creating transportable tablespace sets from backup using RMAN.

Figure 14-1 RMAN Transportable Tablespace From Backup: Architecture

Description of "Figure 14-1 RMAN Transportable Tablespace From Backup: Architecture"

The elements in the diagram and the process RMAN performs are described in the discussion which follows.

The figure contains the following entities:

• The Recovery Manager client

• The source database, containing the tablespaces to be transported

• Archived redo logs and backups from the source database, used in restore and recovery of the tablespaces being transported

• The auxiliary instance, an Oracle database instance which is created by RMAN on the same host as the source database, to perform the restore and recovery of the tablespaces, and, if the process succeeds, cleaned up afterwards.

• The auxiliary set, which includes datafiles and other files required for the tablespace transport process but which are not themselves part of the recovery set. The auxiliary set typically includes:

  • A copy of the SYSTEM and SYSAUX tablespaces

  • Undo tablespaces and datafiles containing rollback or undo segments from the source database

  The auxiliary instance has other files associated with it, such as its own control file, parameter file, and online logs, but they are not part of the auxiliary set.

• The auxiliary destination, a location on disk where auxiliary set files, such as the parameter file, datafiles (other than those of the tablespaces being transported), control files and online logs of the auxiliary instance can be stored while the RMAN TRANSPORT TABLESPACE process is running. If the transport process succeeds, these files are deleted.

  Note:

  Specifying an auxiliary destination is optional; however, if you do not use one, you must ensure that locations are specified for all auxiliary instance files, including all datafiles and online log files, using the initialization parameters of the auxiliary instance.

  Oracle recommends the use of an auxiliary destination to simplify the use of TRANSPORT TABLESPACE. See the rules described in "Customize Other Auxiliary File Locations in TRANSPORT TABLESPACE" for details on the extra steps required if you do not use an auxiliary destination.

• The tablespace destination, a location on disk which (by default) contains the datafile copies and other output files when the tablespace transport command completes

• The transportable set, which consists of the datafiles from the tablespaces to be transported and an export dump file (generated using Data Pump Export) for use when plugging in the tablespaces at a destination database

• The sample import script (generated by RMAN) for use in plugging the tablespaces in at a target database, and an export log containing the output from Data Pump Export

All of these terms will be referenced throughout the remainder of this discussion.

Limitations of RMAN TRANSPORT TABLESPACE Command

The limitations on creating transportable tablespace sets described in Oracle Database Administrator's Guide apply to transporting tablespaces from backup, with the exception of the requirement to make the tablespaces read-only.

There are also limitations specific to creating a transportable tablespace set using RMAN:

• You must have a backup of all needed tablespaces (including those in the auxiliary set) and archived redo log files available for use by RMAN that can be recovered to the target point in time for the TRANSPORT TABLESPACE operation.

  Note:

  If RMAN is not part of the backup strategy for your database, you can still use RMAN TRANSPORT TABLESPACE, as long as the needed datafile copies and archived redo logs are available on disk. Use the RMAN CATALOG command to record the datafile copies and archived logs in the RMAN repository. You can then use TRANSPORT TABLESPACE. See Oracle Database Backup and Recovery Basics for details on using CATALOG.

  You also have the option of using RMAN to back up your database specifically to create backups for use in creating a transportable tablespace set from backup.

• Because the RMAN process for creating transportable tablespaces from backup uses the Data Pump Export and Import utilities, you cannot use this process if the tablespaces to be transported use XMLTypes. In such a case, you must use the process documented in Oracle Database Administrator's Guide.

• Because RMAN creates the automatic auxiliary instance used for restore and recovery on the same host as the source instance, there is some performance overhead during the operation of the TRANSPORT TABLESPACE command.

• If you drop a tablespace, then you cannot later use TRANSPORT TABLESPACE to include that tablespace in a transportable tablespace set, even if the SCN for TRANSPORT TABLESPACE is earlier than the SCN at which the table was dropped.

• If you rename a tablespace, you cannot use TRANSPORT TABLESPACE to create a transportable tablespace set as of a point in time before the tablespace was renamed. (RMAN has no information about the previous name of the tablespace.)

• You cannot TRANSPORT tables without their associated constraints, or constraints without their associated tables.

• Neither the transportable set nor the auxiliary set datafiles can contain any of the following:

  • Replicated master tables

  • Partial tables

  • Tables with VARRAY columns, nested tables, or external files

  • Snapshot logs and snapshot tables

  • Tablespaces containing undo or rollback segments

  • Tablespaces that contain objects owned by SYS, including rollback segments

If you are performing TRANSPORT TABLESPACE without a recovery catalog, the following additional restrictions apply:

• If creating a transportable set with tablespace contents as of a point in time in the past, then the set of tablespaces with undo segments at the time TRANSPORT TABLESPACE is executed must be the same as the set of tablespaces with undo segments at the time selected for transport.

  Tablespaces including undo segments as of the target SCN for TRASNPORT TABLESPACE must be part of the auxiliary set. Unlike the recovery catalog, the RMAN repository in the control file only contains a record of tablespaces that include undo segments at the current time. If the set of tablespaces with undo segments was different at the target time, then TRANSPORT TABLESPACE fails.

• If the database has re-used the control file records for the RMAN repository that contained information about backups required for the TRANSPORT TABLESPACE process, then the process fails because RMAN cannot locate the required backups. You may be able to use CATALOG to add the needed backups to the RMAN repository if they are still available, but if the database is already overwriting control file records you may lose records of other needed backups.

Using RMAN TRANSPORT TABLESPACE: Basic Scenario

This section describes the use of TRANSPORT TABLESPACE in the most automated case.

In this scenario, the AUXILIARY DESTINATION clause is specified, which causes RMAN to use default values that work for most cases in managing the auxiliary instance. Only required options are specified. Oracle recommends that you use an auxiliary destination with TRANSPORT TABLESPACE to simplify management of auxiliary instance files.

To use RMAN TRANSPORT TABLESPACE:

Start the RMAN client, connecting to the source database and, if used, the recovery catalog. Then enter the TRANSPORT TABLESPACE command, specifying the required arguments. For example, to transport the tablespaces tbs_2 and tbs_3, use the TRANSPORT TABLESPACE command as follows:

transport tablespace tbs_2, tbs_3
   tablespace destination '/disk1/transportdest'
   auxiliary destination '/disk1/auxdest'
   ;
 

When the TRANSPORT TABLESPACE command completes, the following outputs result:

• The transportable set datafiles are left in the location /disk1/transportdest with their original names.

• The Data Pump Export dump file for the transportable set is named dmpfile.dmp, the export log is named explog.log and the sample import script is named impscrpt.sql. All are created in the tablespace destination /disk1/transportdest.

  Note:

  If there is already a file under the name of the export dump file in the tablespace destination, then TRANSPORT TABLESPACE fails when it calls Data Pump Export. If repeating a previous TRANSPORT TABLESPACE operation, make sure you delete the previous output files, including the export dump file.

• The auxiliary set files are removed from /disk1/auxdest.

You can now return to the process for transporting tablespaces described in Oracle Database Administrator's Guide.

RMAN TRANSPORT TABLESPACE with UNTIL Time or SCN

If you specify a target time with the TRANSPORT TABLESPACE command, then during the tablespace transport operation, RMAN will restore the tablespace at the auxiliary instance using backups from prior to the target time and perform point-in-time recovery on the auxiliary database to the specified target time. (Backups and redo logs needed for this point-in-time recovery must be available.)

The target time can be specified using an SCN (in the current incarnation or its ancestors), log sequence number, restore point or time expression. For example:

TRANSPORT TABLESPACE tbs_2 
   TABLESPACE DESTINATION '/disk1/transportdest' 
   AUXILIARY DESTINATION '/disk1/auxdest'
   UNTIL SCN 11379;

TRANSPORT TABLESPACE tbs_2 
   TABLESPACE DESTINATION '/disk1/transportdest' 
   AUXILIARY DESTINATION '/disk1/auxdest'
   UNTIL RESTORE POINT 'before_upgrade';

TRANSPORT TABLESPACE tbs_2 
   TABLESPACE DESTINATION '/disk1/transportdest' 
   AUXILIARY DESTINATION '/disk1/auxdest'
   UNTIL TIME 'SYSDATE-1';

RMAN TRANSPORT TABLESPACE: Specifying Locations for Data Pump Files

You can change the names of the Data Pump Export dump file for the transportable set, the sample import script for use at the target database, and the log file generated by Data Pump Export, and the directory to which they are written.

By default, these files are stored in the tablespace destination and named as follows:

• The Data Pump Export dump file is named dmpfile.dmp

• The export log file is named explog.log

• The sample import script is called impscrpt.sql

You can place the dump file and the export log in a different directory by using the DATAPUMP DIRECTORY clause, passing in the name of a database directory object.

These files can be renamed using the DUMP FILE, EXPORT LOG and IMPORT SCRIPT clauses of TRANSPORT TABLESPACE.

The following example illustrates the use of TRANSPORT TABLESPACE with the DATAPUMP DIRECTORY, DUMP FILE, EXPORT LOG and IMPORT SCRIPT filenames specified.

Assume that a database directory object has been created as follows, for use with Data Pump Export:

SQL>  CREATE OR REPLACE DIRECTORY mypumpdir as '/datapumpdest';

The following TRANSPORT TABLESPACE command illustrates the use of the optional arguments that control file output locations:

TRANSPORT TABLESPACE tbs_2
   TABLESPACE DESTINATION '/transportdest'
   AUXILIARY DESTINATION '/auxdest'
   DATAPUMP DIRECTORY  mypumpdir
   DUMP FILE 'mydumpfile.dmp'
   IMPORT SCRIPT 'myimportscript.sql'
   EXPORT LOG 'myexportlog.log';
   

After a successful run, the auxiliary destination is cleaned up, the Data Pump Export Dump file and the export log are located in the directory referenced by DATAPUMP DIRECTORY (/datapumpdest/mydumpfile.dmp and /datapumpdest/myexportlog.log) and the transportable set datafiles are stored in /transportdest.

RMAN TRANSPORT TABLESPACE with Customized Initialization Parameters

When RMAN creates the auxiliary instance, it creates an initialization parameter file with default parameters that should work for nearly all TRANSPORT TABLESPACE cases, especially if you provide an AUXILIARY DESTINATION argument to TRANSPORT TABLESPACE.

RMAN TRANSPORT TABLESPACE can also use an auxiliary instance parameter file, which can contain values for additional initialization parameters, and values that override the values of those parameters defined in the default initialization parameter file.

Reasons for using an auxiliary instance parameter file include:

• To manage locations for auxiliary instance datafiles (if, for instance, you do not want all auxiliary instance datafiles stored in the same location on disk, but you do not want to specify the location of every file individually).

• To specify control naming for online redo logs using LOG_FILE_NAME_CONVERT

• To increase SHARED_POOL_SIZE if needed for Data Pump Export.

SHARED_POOL_SIZE=150M;

RUN {
SET AUXILIARY INSTANCE PARAMETER FILE TO '/tmp/auxinstparams.ora';
TRANSPORT TABLESPACE tbs_2 
   TABLESPACE DESTINATION '/disk1/transportdest' 
   AUXILIARY DESTINATION '/disk1/auxdest';
} 

Customize Shared Pool Size in RMAN TRANSPORT TABLESPACE

If the default shared pool size of 100MB is not sufficient for Data Pump Export to run successfully, then specify a larger value. Use an auxiliary instance parameter file as described in "RMAN TRANSPORT TABLESPACE with Customized Initialization Parameters". Include the SHARED_POOL_SIZE initialization parameter in your auxiliary instance parameter file, listing the control file locations desired.

For more on the use of the SHARED_POOL_SIZE initialization parameter, see Oracle Database Reference.

Customize Auxiliary Control File Location in TRANSPORT TABLESPACE

By default, one control file is created for the auxiliary instance, in an operating system dependent location. (In Unix, the default location is ?/dbs/cntrl_@.dbf, where '?' stands for ORACLE_HOME and '@' stands for ORACLE_SID. For an automatic auxiliary instance, ORACLE_SID is randomly generated by RMAN).

To change the location of the auxiliary instance control file, use an auxiliary instance parameter file as described in "RMAN TRANSPORT TABLESPACE with Customized Initialization Parameters". Include the CONTROL_FILES initialization parameter in your auxiliary instance parameter file, listing the control file locations desired.

For more on the use of the CONTROL_FILES initialization parameter, see Oracle Database Reference.

Customize Other Auxiliary File Locations in TRANSPORT TABLESPACE

Several different rules affect the location of auxiliary instance files such as datafiles and online logs, created during TRANSPORT TABLESPACE. The simplest method is to use AUXILIARY DESTINATION and let RMAN manage all file locations automatically. However, if you need to relocate some or all auxiliary instance files, the options for specifying locations for these files are described here in order of precedence, so that, if several are used, then for each file, the first rule in the list that applies determines the filename.

• Transport Tablespace with SET NEWNAME for Auxiliary Datafiles

• Transport Tablespace with CONFIGURE AUXNAME for Auxiliary Datafiles

• Transport Tablespace with AUXILIARY DESTINATION Parameter

• Transport Tablespace and Naming Auxiliary Files with Initialization Parameters

RUN {
   SET NEWNAME FOR DATAFILE '/oracle/dbs/tbs_12.f' 
      TO '/bigdrive/auxdest/tbs_12.f';
   SET NEWNAME FOR DATAFILE '/oracle/dbs/tbs_11.f'
      TO '/bigdrive/auxdest/tbs_11.f';
   TRANSPORT TABLESPACE tbs_2 
         TABLESPACE DESTINATION '/disk1/transportdest' 
         AUXILIARY DESTINATION '/disk1/auxdest';
   }

CONFIGURE AUXNAME FOR '/oracle/dbs/tbs_12.f' TO '/disk1/auxdest/tbs_12.f';
 

TRANSPORT TABLESPACE tbs_1 AUXILIARY DESTINATION '/myauxdest';

Troubleshooting RMAN TRANSPORT TABLESPACE: Insufficient Shared Pool

If you see an error related to shared pool size, create an auxiliary instance parameter file with a larger value for SHARED_POOL_SIZE, as described in "Customize Shared Pool Size in RMAN TRANSPORT TABLESPACE" .

Troubleshooting RMAN TRANSPORT TABLESPACE: Filename Conflicts

If your SET NEWNAME, CONFIGURE AUXNAME and DB_FILE_NAME_CONVERT cause multiple files in the auxiliary or recovery sets to have the same name, RMAN will report an error during the TRANSPORT TABLESPACE command. To correct the problem, use different values for these parameters to ensure that duplicate file names are not created.