8 Performing Oracle ASM Data Migration with RMAN

Overview of Oracle ASM Data Migration

This section explains the basic concepts and tasks involved in migrating data to and from Oracle ASM.

This section includes the following topics:

• Purpose of Oracle ASM Data Migration

• Basic Concepts of Oracle ASM Data Migration

• Basics Steps of Data Migration to Oracle ASM Using RMAN

Preparing to Migrate the Database to Oracle ASM Using RMAN

This section explains how to prepare the database for migration. This section makes the following assumptions:

• You want to migrate the database to two Oracle ASM disk groups: +DATA for the database and +FRA for the fast recovery area.

• The database to be migrated to Oracle ASM storage is named mydb.

To prepare the database for Oracle ASM migration:

1. If the COMPATIBLE initialization parameter setting for the database is less than 11.0.0, then make any read-only transportable tablespaces read/write.

   Read-only transportable tablespaces cannot be migrated because RMAN cannot back them up.

2. If the database is a physical standby database, and if managed recovery is started, then stop managed recovery.

   A physical standby database is a copy of a production database that you can use for disaster protection.

   For example, connect SQL*Plus to the database with SYSDBA privileges, and run the following statement to stop managed recovery:

   SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
   

   Keep this terminal window open.

3. Copy the server parameter file or initialization parameter file to a temporary location.

   The following example uses an operating system utility to copy the server parameter file:

   $ cp spfileMYDB.ora orig_spfileMYDB.ora
   

4. In a new terminal window, start RMAN session and connect as TARGET to the database to be migrated. Optionally, connect to a recovery catalog.

5. Back up the data files to the Oracle ASM disk group.

   The following example uses a RUN command to make a level 0 incremental backup and allocates four channels to increase the backup speed. A level 0 incremental backup is an RMAN incremental backup that backs up all data blocks in the data files being backed up. An incremental backup at level 0 is identical in content to a full backup, but unlike a full backup the level 0 backup is considered a part of the incremental backup strategy.

   An incremental backup is a RMAN backup in which only modified blocks are backed up. Incremental backups are classified by level. A level 0 incremental backup performs the same function as a full backup in that they both back up all blocks that have ever been used. The difference is that a full backup does not affect blocks backed up by subsequent incremental backups, whereas an incremental backup affects blocks backed up by subsequent incremental backups.

   A full backup is a non-incremental RMAN backup. Full does not refer to how much of the database is backed up, but to the fact that the backup is not incremental. Consequently, you can make a full backup of one data file.

   Increase or decrease this number accordingly. The format clause specifies +DATA, which is the name of the Oracle ASM disk group to be used for storing the database.

   RUN
   {
     ALLOCATE CHANNEL dev1 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev2 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev3 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev4 DEVICE TYPE DISK;
     BACKUP AS COPY
       INCREMENTAL LEVEL 0
       DATABASE
       FORMAT '+DATA'
       TAG 'ORA_ASM_MIGRATION';
   }
   

6. If block change tracking is enabled for the database, then optionally make a level 1 incremental backup that you can use later to recover the database copy.

   Block change tracking is a database option that causes Oracle to track data file blocks affected by each database update. The tracking information is stored in a block change tracking file. When block change tracking is enabled, RMAN uses the record of changed blocks from the change tracking file to improve incremental backup performance by only reading those blocks known to have changed, instead of reading data files in their entirety.

   The following example makes an incremental level 1 copy of the level 0 backup created in the previous step:

   RUN
   {
     ALLOCATE CHANNEL dev1 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev2 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev3 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev4 DEVICE TYPE DISK;
     BACKUP INCREMENTAL LEVEL 1 
       FOR RECOVER OF COPY WITH TAG 'ORA_ASM_MIGRATION' 
       DATABASE;
   }
   

7. If the database is in ARCHIVELOG mode, and if the database is open, then archive the online logs.

   The following example uses the SQL command to archive the current redo logs:

   RMAN> SQL "ALTER SYSTEM ARCHIVE LOG CURRENT";
   

8. If the database instance is currently using a server parameter file, then back it up.

   The following example backs up the server parameter file:

   RMAN> BACKUP AS BACKUPSET SPFILE;
   

9. If block change tracking is enabled, then disable it.

   The following command disables block change tracking:

   RMAN> SQL "ALTER DATABASE DISABLE BLOCK CHANGE TRACKING";
   

10. If Flashback Database is enabled, then disable it and drop any guaranteed restore points.

    Note:

    If you are not migrating the fast recovery area, then skip this step.

    Disabling Oracle Flashback Database is necessary because you cannot migrate flashback logs to Oracle ASM. The following command disables Flashback Database:

    RMAN> SQL "ALTER DATABASE FLASHBACK OFF";
    

    The following command drops the guaranteed restore point named Q106:

    RMAN> SQL "DROP RESTORE POINT Q106";
    

11. Shut down the database consistently.

    The following command shuts down the database:

    RMAN> SHUTDOWN IMMEDIATE;
    

Migrating the Database to Oracle ASM Using RMAN

The following procedure is intended to minimize database downtime. The steps differ slightly depending on whether you are migrating a primary or standby database. The procedure makes the same assumptions described in "Preparing to Migrate the Database to Oracle ASM Using RMAN". If you are not migrating the recovery area to Oracle ASM, then you must modify some steps, which are noted.

To migrate the database to Oracle ASM:

1. Follow the steps in "Preparing to Migrate the Database to Oracle ASM Using RMAN".

2. Restore or create a server parameter file in Oracle ASM storage.

   The steps depend on whether the database is using a server parameter file:

   • If the database is using a server parameter file, then restore it to the Oracle ASM disk group with the following commands, where sid is the SID of the instance:

     RMAN> STARTUP MOUNT;
     RMAN> RESTORE SPFILE TO '+DATA/spfilesid.ora';
     RMAN> SHUTDOWN IMMEDIATE;
     

   • If the database is not using a server parameter file, then create one in Oracle ASM. Run the CREATE SPFILE command in SQL*Plus as follows, where sid is the SID of the database (the command spans two lines):

     SQL> CREATE SPFILE='+DATA/spfilesid.ora' FROM PFILE='?/dbs/initsid.ora';
     

     Afterward, delete spfilesid.ora and initsid.ora from the ?/dbs directory and create a new initsid.ora with the following line of content:

     SPFILE='+DATA/spfilesid.ora'
     

3. Set Oracle Managed Files initialization parameters to Oracle ASM locations.

   Note:

   If you are not migrating the fast recovery area, then do not change the DB_RECOVERY_FILE_DEST and DB_RECOVERY_FILE_DEST_SIZE initialization parameter settings. However, you must set DB_CREATE_ONLINE_LOG_DEST_n parameter to an Oracle ASM location for migration of the online redo logs.

   Set the DB_CREATE_FILE_DEST and optional DB_CREATE_ONLINE_LOG_DEST_n initialization parameters to Oracle ASM disk groups. If the database uses a recovery area, then change the recovery area location to the Oracle ASM disk group. Also, change the recovery area size.

   Run commands in SQL*Plus as shown in the following example. The example assumes that the size of the fast recovery area is 100 GB and specifies the disk group +FRA for the fast recovery area.

   SQL> STARTUP FORCE NOMOUNT;
   SQL> ALTER SYSTEM SET DB_CREATE_FILE_DEST='+DATA' SID='*';
   SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE=100G SID='*';
   SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST='+FRA' SID='*';
   

4. Set the CONTROL_FILES initialization parameter to Oracle ASM locations.

   If you are migrating the fast recovery area, then enter the following commands in SQL*Plus to restart the database instance and set the control file locations to disk groups +DATA and +FRA:

   SQL> STARTUP FORCE NOMOUNT;
   SQL> ALTER SYSTEM SET CONTROL_FILES='+DATA','+FRA' SCOPE=SPFILE SID='*';
   

   If you are not migrating the fast recovery area, then enter the following commands in SQL*Plus to restart the database instance and set the control file locations to disk group +DATA:

   SQL> STARTUP FORCE NOMOUNT;
   SQL> ALTER SYSTEM SET CONTROL_FILES='+DATA','+DATA' SCOPE=SPFILE SID='*';
   

5. Migrate the control file to Oracle ASM and mount the control file.

   Switch to the RMAN terminal to restore the control file. In the following example, original_cf_name is a control file name in the initialization parameter file before migration:

   RMAN> STARTUP FORCE NOMOUNT;
   RMAN> RESTORE CONTROLFILE FROM 'original_cf_name';
   RMAN> ALTER DATABASE MOUNT;
   

6. Migrate the data files to Oracle ASM.

   Use RMAN to switch to the database copy that you created in step 5 "Back up the data files to the Oracle ASM disk group" in "Preparing to Migrate the Database to Oracle ASM Using RMAN". The switch renames all the data files to files on Oracle ASM disk groups. Afterward, recover the database. If incremental backups were taken, then RMAN applies them during recovery. For example, enter the following commands at the RMAN prompt:

   SWITCH DATABASE TO COPY;
   RUN
   {
     ALLOCATE CHANNEL dev1 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev2 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev3 DEVICE TYPE DISK;
     ALLOCATE CHANNEL dev4 DEVICE TYPE DISK;
     RECOVER DATABASE;
   }
   

7. If the database uses block change tracking or Flashback Database, then enable these features.

   Note:

   If you are not migrating the recovery area, then you do not enable Flashback Database unless you had disabled it previously.

   For example, enter the following statements in SQL*Plus:

   SQL> ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE '+DATA';
   SQL> ALTER DATABASE FLASHBACK ON;
   

8. Place the database in its normal operation mode.

   The normal operational mode depends on whether the database is a primary or standby database:

   • If the database is a primary database, then open it as follows:

     SQL> ALTER DATABASE OPEN;
     

   • If the database is a standby database, then resume managed recovery mode as follows:

     SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE;
     

9. Drop the tempfiles and re-create them in Oracle ASM.

   Use SQL*Plus to re-create the tempfiles. In the following example, the name of the tempfile in the original storage is tempfile_name. The name of the temporary tablespace is temp_tbs_name.

   SQL> ALTER DATABASE TEMPFILE 'tempfile_name' DROP;
   SQL> ALTER TABLESPACE temp_tbs_name ADD TEMPFILE;
   

10. Migrate the online redo log files.

    If this is a primary database, then add new log group members in Oracle ASM and drop the old members. You can use the following PL/SQL script to migrate the online redo log groups into an Oracle ASM disk group. The PL/SQL script assumes that the Oracle Managed Files initialization parameters specified in step 3 "Set Oracle Managed Files initialization parameters to Oracle ASM locations" in "Migrating the Database to Oracle ASM Using RMAN" are set.

    Example 8-1 Migrating the online redo logs

    SET SERVEROUTPUT ON;
    DECLARE
       CURSOR rlc IS
          SELECT GROUP# GRP, THREAD# THR, BYTES, 'NO' SRL
          FROM   V$LOG
          UNION
          SELECT GROUP# GRP, THREAD# THR, BYTES, 'YES' SRL
          FROM   V$STANDBY_LOG
          ORDER BY 1;
       stmt     VARCHAR2(2048);
    BEGIN
       FOR rlcRec IN rlc LOOP
          IF (rlcRec.srl = 'YES') THEN
             stmt := 'ALTER DATABASE ADD STANDBY LOGFILE THREAD ' ||
                     rlcRec.thr || ' SIZE ' || rlcRec.bytes;
             EXECUTE IMMEDIATE stmt;
             stmt := 'ALTER DATABASE DROP STANDBY LOGFILE GROUP ' || rlcRec.grp;
             EXECUTE IMMEDIATE stmt;
          ELSE
             stmt := 'ALTER DATABASE ADD LOGFILE THREAD ' ||
                     rlcRec.thr || ' SIZE ' ||  rlcRec.bytes;
             EXECUTE IMMEDIATE stmt;
             BEGIN
                stmt := 'ALTER DATABASE DROP LOGFILE GROUP ' || rlcRec.grp;
                DBMS_OUTPUT.PUT_LINE(stmt);
                EXECUTE IMMEDIATE stmt;
             EXCEPTION
                WHEN OTHERS THEN
                   EXECUTE IMMEDIATE 'ALTER SYSTEM SWITCH LOGFILE';
                   EXECUTE IMMEDIATE 'ALTER SYSTEM CHECKPOINT GLOBAL';
                   EXECUTE IMMEDIATE stmt;
             END;
          END IF;
       END LOOP;
    END;
    /
    

11. Optionally, migrate backups and copies in the old fast recovery area to Oracle ASM as follows:

    1. If foreign archived logs exists in the recovery area, then you cannot migrate them to Oracle ASM. Run the following command at the RMAN prompt:

       RMAN> DELETE REMOTE ARCHIVELOG ALL;
       

    2. Back up archived redo log files, backup sets, and data file copies to Oracle ASM. For example, run the following command at the RMAN prompt:

       RUN
       {
         ALLOCATE CHANNEL dev1 DEVICE TYPE DISK;
         ALLOCATE CHANNEL dev2 DEVICE TYPE DISK;
         ALLOCATE CHANNEL dev3 DEVICE TYPE DISK;
         ALLOCATE CHANNEL dev4 DEVICE TYPE DISK;
       
         BACKUP AS COPY ARCHIVELOG ALL DELETE INPUT;
         BACKUP BACKUPSET ALL DELETE INPUT;
         BACKUP AS COPY DATAFILECOPY ALL DELETE INPUT;
       }
       

Migrating a Database from Oracle ASM to Alternative Storage

Migrating a database from Oracle ASM to an alternative storage system is essentially the reverse of the migration to Oracle ASM. Modify the steps in "Preparing to Migrate the Database to Oracle ASM Using RMAN" and "Migrating the Database to Oracle ASM Using RMAN" as follows:

• If the procedure specifies Oracle Managed Files locations, then alter the procedure to use locations in alternative storage.

• If the FORMAT clause of the BACKUP command specifies an Oracle ASM location, then change the backup format to an alternative storage location.

• If a filename used in a SQL statement is an Oracle ASM location, then change it to a filename in the alternative storage location.

Moving Data Files Between Oracle ASM Disk Groups Using RMAN

You may want to move an active data file in an ARCHIVELOG mode database from one Oracle ASM disk group to another. In this case, you use BACKUP AS COPY to copy the data file to the new disk group and SET NEWNAME and SWITCH commands to rename the data file in the control file.

For this scenario, assume that you are using disk groups DATA and USERDATA. You want to move data file +DATA/orcl/datafile/users.261.689589837 to disk group USERDATA.

Ensure that ARCHIVELOG mode is enabled for the database before beginning the procedure to move data files.

To move a data file from one Oracle ASM disk group to another disk group, perform the following steps.

1. Start RMAN and connect to the target database.

   For example:

   $ rman
   RMAN> CONNECT TARGET SYS@orcl
   target database Password: XXXXXXXXX
   connected to target database: ORCL (DBID=1217369048)
   

2. Generate a report that shows the names of the data files.

   Run the following REPORT command after connecting RMAN to the target database. Note the data file name of the file to be moved.

   For example:

   RMAN> REPORT SCHEMA;
   
   Report of database schema for database with db_unique_name ORCL
    
   List of Permanent Datafiles
   ===========================
   File Size(MB) Tablespace           RB segs Datafile Name
   ---- -------- -------------- ------- ------------------------
   1    740      SYSTEM         ***     +DATA/orcl/datafile/system.258.689589737
   2    570      SYSAUX         ***     +DATA/orcl/datafile/sysaux.259.689589785
   3    55       UNDOTBS1       ***     +DATA/orcl/datafile/undotbs1.260.689589831
   4    5        USERS          ***     +DATA/orcl/datafile/users.261.689589837
   
   List of Temporary Files
   =======================
   File Size(MB) Tablespace           Maxsize(MB) Tempfile Name
   ---- -------- -------------- ----------- --------------------
   1    20       TEMP           32767       +DATA/orcl/tempfile/temp.262.689589851
   

3. Back up the data file to the new Oracle ASM disk group.

   Run the BACKUP AS COPY command to back up the data file on DATA to USERDATA.

   For example:

   RMAN> BACKUP AS COPY
           DATAFILE "+DATA/orcl/datafile/users.261.689589837"
           FORMAT   "+USERDATA";
   
   Starting backup at 16-JUN-09
   allocated channel: ORA_DISK_1
   channel ORA_DISK_1: SID=51 device type=DISK
   channel ORA_DISK_1: starting datafile copy
   input datafile file number=00004 name=+DATA/orcl/datafile/users.261.689589837
   output file name=+USERDATA/orcl/datafile/users.256.689682663
     tag=TAG20090616T103101 RECID=13 STAMP=689682663
   channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01
   Finished backup at 16-JUN-09
   

   You could also specify the data file by the data file number and data file type.

   For example:

   BACKUP AS COPY
     DATAFILE 4
     FORMAT   "+USERDATA";
   

4. Offline the data file that you intend to move to a new disk group.

   Run the following SQL command in the RMAN client. Note that you use two single quotation marks around the name of the data file, not double quotation marks.

   For example:

   RMAN> SQL "ALTER DATABASE DATAFILE 
          ''+DATA/orcl/datafile/users.261.689589837'' OFFLINE";
   
   sql statement: ALTER DATABASE DATAFILE
        ''+DATA/orcl/datafile/users.261.689589837''  OFFLINE
   

5. Point the control file to the newly created copy of the data file.

   Run the SWITCH...TO COPY command in the RMAN client. The TO COPY option of SWITCH switches the data file to the most recent copy of the data file.

   For example:

   RMAN> SWITCH DATAFILE "+DATA/orcl/datafile/users.261.689589837" TO COPY;
   
   datafile 4 switched to datafile copy
       "+USERDATA/orcl/datafile/users.256.689682663"
   

   The output of this command displays the new name of the data file.

6. Recover the renamed data file.

   Run the RECOVER command in the RMAN client.

   For example:

   RMAN> RECOVER DATAFILE "+USERDATA/orcl/datafile/users.256.689682663";
   
   Starting recover at 16-JUN-09
   using channel ORA_DISK_1
   starting media recovery
   media recovery complete, elapsed time: 00:00:01
   Finished recover at 16-JUN-09
   

7. Bring the data file online.

   Run the SQL command in the RMAN client. Note that you use two single quotation marks around the name of the data file, not double quotation marks.

   For example:

   RMAN> SQL "ALTER DATABASE DATAFILE
         ''+USERDATA/orcl/datafile/users.256.689682663'' ONLINE";
   
   sql statement: ALTER DATABASE DATAFILE
      ''+USERDATA/orcl/datafile/users.256.689682663'' ONLINE
   

8. Delete the data file copy from the original Oracle ASM disk group.

   In this scenario, +DATA/orcl/datafile/users.261.689589837 is the original data file in DATA. Because you issued SET NEWNAME and SWITCH commands for this data file, the original file is now recorded in the RMAN repository as a data file copy. Run a DELETE command in the RMAN client to remove this file.

   For example:

   RMAN> DELETE DATAFILECOPY "+DATA/orcl/datafile/users.261.689589837";
   
   released channel: ORA_DISK_1
   allocated channel: ORA_DISK_1
   channel ORA_DISK_1: SID=51 device type=DISK
   List of Datafile Copies
   =======================
   Key     File S Completion Time Ckp SCN    Ckp Time       
   ------- ---- - --------------- ---------- ---------------
   14      4    A 16-JUN-09       864471     16-JUN-09      
           Name: +DATA/orcl/datafile/users.261.689589837
           Tag: TAG20090615T084217
   
   Do you really want to delete the above objects (enter YES or NO)? y
   deleted datafile copy
   datafile copy file name=+DATA/orcl/datafile/users.261.689589837 RECID=14 STAMP=689683255
   Deleted 1 objects