How to extract controlfiles, datafiles, and archived logs from SMR backupsets without using RMAN

Introduction:

 When using RMAN to restore objects (datafiles, controlfiles, or archivelogs) from backupsets, the object restore can be driven from the recovery catalog or the target database controlfile. This note explains how to extract objects from backupsets when the recovery catalog and controlfiles have been lost. In this scenario, you effectively perform the RMAN functions through PL/SQL procedure calls.

Contents:

 1. Prerequisites
 2. Extracting the controlfile from a backupset
 3. Extracting datafiles from a backupset
 4. Applying incrementals
 5. Extracting archivelogs from a backupset
 6. A typical scenario
 7. Errors
 8. Things to be done

1. Prerequisites

 The customer must have a knowledge of the contents of backupsets i.e. what they contain, when the backups were created, and the type of backups. Ideally they should have logs of the RMAN backup sessions that produced the backupsets.

 Note that the following anonymous PL/SQL blocks are run on the instance of the database being recovered (the 'target'). The instance must be at least started (once the controlfile has been restored the database can also be mounted). Anonymous blocks can be executed in this manner as long as they call only 'fixed' packages. The DBMS_BACKUP_RESTORE packages are fixed. 
 IMPORTANT: All the anonymous blocks must be executed by SYS or a user who has execute privilege on SYS.DBMS_BACKUP_RESTORE

2. Extracting the controlfile from a backupset

 The first stage is to extract the controlfile from a backupset. This is achieved by making use of the following SYS.DBMS_BACKUP_RESTORE packaged functions & procedures:

   FUNCTION deviceAllocate  - allocates a device for sequential I/O
   PROCEDURE restoreSetDataFile - begins a restore conversation
   PROCEDURE restoreControlfileTo - specifies the controlfile destination
   PROCEDURE restoreBackupPiece  - performs the restore
   PROCEDURE deviceDeallocate  - deallocates the I/O device

 The following anonymous block can be created and executed to restore a controlfile from a backupset. Before executing it, you MUST edit the block as follows:

   a. The filetable PL/SQL table entries must reflect the backuppieces comprising the backupset
   b. The v_maxPieces variable must reflect the number of backuppieces comprising the backupset
   c. The call to restoreControlfileTo must specify the correct controlfile path & filename

 IMPORTANT: The latest backup of the controlfile should be restored. Because recovery (using backup controlfile) will be performed manually, the recovering session will need to start applying redo from the current log sequence AT THE TIME OF THE CONTROLFILE BACKUP.  Thus, to take advantage of incremental backups, restore a controlfile taken along with the incremental backups, thus reducing the amount of redo required during recovery.

DECLARE

 v_dev  varchar2(50); -- device type allocated for restore
 v_done  boolean; -- has the controlfile been fully extracted yet
 type t_fileTable is table of varchar2(255)
   index by binary_integer;
 v_fileTable  t_fileTable; -- Stores the backuppiece names
 v_maxPieces  number:=1; -- Number of backuppieces in backupset

BEGIN

-- Initialise the filetable & number of backup pieces in the backupset
-- This section of code MUST be edited to reflect the customer's available
-- backupset before the procedure is compiled and run. In this example, the
-- backupset consists of 4 pieces:

 v_fileTable(1):='fulldb_s15_p1';
 v_fileTable(2):='fulldb_s15_p2';
 v_fileTable(3):='fulldb_s15_p3';
 v_fileTable(4):='fulldb_s15_p4';
 v_maxPieces:=4;

-- Allocate a device. In this example, I have specified 'sbt_tape' as I am
-- reading backuppieces from the media manager. If the backuppiece is on disk,
-- specify type=>null

 v_dev:=sys.dbms_backup_restore.deviceAllocate(type=>'sbt_tape', ident=>'t1');

-- Begin the restore conversation

 sys.dbms_backup_restore.restoreSetDatafile;

-- Specify where the controlfile is to be recreated

 sys.dbms_backup_restore.restoreControlfileTo(cfname=>'/support2/OFA_V804/u1/oradata/dbs/ctrl1V804.ctl');

-- Restore the controlfile

 FOR i IN 1..v_maxPieces LOOP
   sys.dbms_backup_restore.restoreBackupPiece(done=>v_done,
     handle=>v_fileTable(i), params=>null);

   IF v_done THEN
     GOTO all_done;
   END IF;
 END LOOP;

<<all_done>> -- Deallocate the device

 sys.dbms_backup_restore.deviceDeallocate;

END; /

3. Extracting datafiles from a backupset

 The second stage is to extract the datafiles from a backupset. This is achieved by making use of the following SYS.DBMS_BACKUP_RESTORE packaged functions & procedures:

   FUNCTION deviceAllocate             - allocates a device for sequential I/O
   PROCEDURE restoreSetDataFile        - begins a restore conversation
   PROCEDURE restoreDataFileTo       - datafile number & destination
   PROCEDURE restoreBackupPiece        - performs the restore
   PROCEDURE deviceDeallocate          - deallocates the I/O device

 The following anonymous block can be created and executed to restore a datafile from a backupset. Before executing it, you MUST edit the block as follows:

   a. The filetable PL/SQL table entries must reflect the backuppieces comprising the backupset
   b. The v_maxPieces variable must reflect the number of backuppieces comprising the backupset
   c. The call to restoreDataFileTo must specify the correct datafile number, and datafile path & filename

DECLARE

 v_dev  varchar2(50);  -- device type allocated for restore
 v_done boolean:=false; -- has the datafile been fully extracted yet
 type t_fileTable is table of varchar2(255)
   index by binary_integer;
 v_fileTable  t_fileTable;  -- Stores the backuppiece names
 v_maxPieces  number:=1;  -- Number of backuppieces in backupset

BEGIN

-- Initialise the filetable & number of backup pieces in the backupset
-- This section of code MUST be edited to reflect the customer's available
-- backupset before the procedure is compiled and run. In this example, the
-- backupset consists of 4 pieces:

 v_fileTable(1):='fulldb_s15_p1';
 v_fileTable(2):='fulldb_s15_p2';
 v_fileTable(3):='fulldb_s15_p3';
 v_fileTable(4):='fulldb_s15_p4';
 v_maxPieces:=4;

-- Allocate a device. In this example, I have specified 'sbt_tape' as I am
-- reading backuppieces from the media manager. If the backuppiece is on disk,
-- specify type=>null

 v_dev:=sys.dbms_backup_restore.deviceAllocate(type=>'sbt_tape',

ident=>'t1');

-- Begin the restore conversation

 sys.dbms_backup_restore.restoreSetDatafile;

-- Specify where the datafile is to be recreated

 sys.dbms_backup_restore.restoreDataFileTo(dfnumber=>1,

toname=>'/support2/OFA_V804/u1/oradata/dbs/sysV804.dbf');

-- Restore the datafile

 FOR i IN 1..v_maxPieces LOOP
   sys.dbms_backup_restore.restoreBackupPiece(done=>v_done,

handle=>v_fileTable(i), params=>null);

   IF v_done THEN
     GOTO all_done;
   END IF;
 END LOOP;

<<all_done>> -- Deallocate the device

 sys.dbms_backup_restore.deviceDeallocate;

END; /

4. Applying incrementals

 If incrementals are to be applied, you must execute this anonymous block for each incremental datafile backup. The following SYS.DBMS_BACKUP_RESTORE packaged functions & procedures are called:

   FUNCTION deviceAllocate             - allocates a device for sequential I/O
   PROCEDURE applySetDataFile          - begins a restore conversation
   PROCEDURE applyDataFileTo           - datafile number & destination
   PROCEDURE applyBackupPiece          - performs the restore
   PROCEDURE deviceDeallocate          - deallocates the I/O device

 The following anonymous block can be created and executed to restore a datafile from a backupset. Before executing it, you MUST edit the block as follows:

   a. The filetable PL/SQL table entries must reflect the backuppieces comprising the backupset
   b. The v_maxPieces variable must reflect the number of backuppieces comprising the backupset
   c. The call to applyDataFileTo must specify the correct datafile number, and datafile path & filename

DECLARE

 v_dev           varchar2(50);           -- device type allocated for restore
 v_done          boolean:=false;  -- has the datafile been fully extracted yet
 type t_fileTable is table of varchar2(255)
   index by binary_integer;
 v_fileTable     t_fileTable;            -- Stores the backuppiece name
 v_maxPieces     number:=1;              -- Number of backuppieces in backupset

BEGIN

-- Initialise the filetable & number of backup pieces in the backupset
-- This section of code MUST be edited to reflect the customer's available
-- backupset before the procedure is compiled and run. In this example, the
-- backupset consists of 1 piece, a level 2 backupset:

 v_fileTable(1):='fulldb_level2_s18_p1';
 v_maxPieces:=1;

-- Allocate a device. In this example, I have specified 'sbt_tape' as I am
-- reading backuppieces from the media manager. If the backuppiece is on disk,
-- specify type=>null

 v_dev:=sys.dbms_backup_restore.deviceAllocate(type=>'sbt_tape',
                                               ident=>'t1');

-- Begin the restore conversation

 sys.dbms_backup_restore.applySetDataFile;

-- Specify where the datafile is to be recreated

 sys.dbms_backup_restore.applyDataFileTo(dfnumber=>1,
               toname=>'/support2/OFA_V804/u1/oradata/dbs/sysV804.dbf');

-- Restore the datafile

 FOR i IN 1..v_maxPieces LOOP
   sys.dbms_backup_restore.applyBackupPiece(done=>v_done,
                                            handle=>v_fileTable(i),
                                            params=>null);
   IF v_done THEN
     GOTO all_done;
   END IF;
 END LOOP;

<<all_done>> -- Deallocate the device

 sys.dbms_backup_restore.deviceDeallocate;

END; /

5. Extracting archivelogs from a backupset

 The last restore stage is to extract the archivelogs from a backupset. This is achieved by making use of the following SYS.DBMS_BACKUP_RESTORE packaged functions & procedures:

   FUNCTION deviceAllocate             - allocates a device for sequential I/O
   PROCEDURE restoreSetArchivedLog     - begins a restore conversation
   PROCEDURE restoreArchivedLog        - archivelog sequence & thread numbers
   PROCEDURE restoreBackupPiece        - performs the restore
   PROCEDURE deviceDeallocate          - deallocates the I/O device

 The following anonymous block can be created and executed to restore an archivelog from a backupset. Before executing it, you MUST edit the block as follows:

   a. The filetable PL/SQL table entries must reflect the backuppieces comprising the backupset
   b. The v_maxPieces variable must reflect the number of backuppieces comprising the backupset
   c. The call to restoreSetArchivedLog must specify the destination where the archivelog is to be restored. Ideally the destination string should be the same as init.ora:log_archive_dest
   d. The call to restoreArchivedLog must specify the log sequence number and thread number of the archivelog

DECLARE

 v_dev   varchar2(50); -- device type allocated for restore
 v_done  boolean:=false; -- has the log been fully extracted yet
 type t_fileTable is table of varchar2(255)
   index by binary_integer;
 v_fileTable  t_fileTable; -- Stores the backuppiece names
 v_maxPieces  number:=1; -- Number of backuppieces in backupset

BEGIN

-- Initialise the filetable & number of backup pieces in the backupset
-- This section of code MUST be edited to reflect the customer's available
-- backupset before the procedure is compiled and run. In this example, the
-- archivelog backupset consists of 2 pieces:

  v_fileTable(1):='al_s20_p1';
  v_fileTable(2):='al_s20_p2';
  v_maxPieces:=2;

-- Allocate a device. In this example, I have specified 'sbt_tape' as I am
-- reading backuppieces from the media manager. If the backuppiece is on disk,
-- specify type=>null

 v_dev:=sys.dbms_backup_restore.deviceAllocate(type=>'sbt_tape',

ident=>'t1');

-- Begin the restore conversation

 sys.dbms_backup_restore.restoreSetArchivedLog(destination=>'/support2/OFA_V804/app/oracle/admin/arch/arch_');

-- Specify where the archivelog is to be recreated

 sys.dbms_backup_restore.restoreArchivedLog(thread=>1,
           sequence=>100);

-- Restore the archivelog

 FOR i IN 1..v_maxPieces LOOP
   sys.dbms_backup_restore.restoreBackupPiece(done=>v_done,

handle=>v_fileTable(i), params=>null);

   IF v_done THEN
     GOTO all_done;
   END IF;
 END LOOP;

<<all_done>> -- Deallocate the device

 sys.dbms_backup_restore.deviceDeallocate;

END; /

 For restoring multiple archives from a backupset, add a loop
 around  sys.dbms_backup_restore.restoreArchivedLog()

 for seq in <min seq#>..<max seq#> loop
   sys.dbms_backup_restore.restoreArchivedLog(thread=>1,
                                            sequence=>seq);
 end loop

6. A typical scenario

 A customer has backupsets consisting of:
   o. an incremental level 0 database backup
   o. an incremental level 2 database backup
   o. archivelogs from the time of the level 2 backup to the current time
 The target database and recovery catalog have been irretrievably lost.

 In this situation, the following steps should be followed (using the above anonymous blocks):
   1. Start the target instance (nomount)
   2. Restore the latest controlfile, ideally from the same backupset as the last incremental to be restored (make further copies if necessary as per the init.ora)
   3. Mount the database
   4. Restore the datafiles from the level 0 backupset
   5. Restore (apply) the datafiles from the level 2 backupset
   6. Restore the archivelogs from the archivelog backupset
   7. Using tradtional v7 recovery techniques, recover the database (until cancel using backup controlfile)
   8. Open the database (resetlogs)
   9. Rebuild the recovery catalog & re-register the target database
  10. Make backups of the target database and recovery catalog database

8. Errors

 8.1 ORA-19615 & ORA-19613 when attempting to extract files

    Errorstack:
      ORA-19583: conversation terminated due to error
      ORA-19615: some files not found in backup set
      ORA-19613: datafile <file#> not found in backup set
      ORA-06512: at "SYS.X$DBMS_BACKUP_RESTORE", line 1043
      ORA-06512: at line 40

    The problem is that one or more backup pieces specified in the v_fileTable table contain NO blocks for the datafile that you are trying to extract.

    For example, I may have run an RMAN backup and allocated 2 channels to backup the (4 datafile) database. This will create 2 backupsets.
                                       
                                                                         +- Backup piece 1a
                   +- (Backupset 1) Datafiles 1,2 -+
                    |                                                    +- Backup piece 2a
Database -+
                    |                                                    +- Backup piece 1b
                   +- (Backupset 2) Datafiles 3,4 -+
                                                                         +- Backup piece 2b

    Although the backup pieces may contain blocks from all datafiles associated with their backupset, they will not contain blocks from a different backupset i.e. pieces 1a and 1b will NOT contain blocks from datafiles 3 or 4.

    If I want to restore datafile 1, and include either backup pieces 1b or 2b in v_fileTable, I will get the errorstack above.

    This is why it is important to know what files are in what backupset.  The original RMAN backup log will help here.

8. Things to be done

 8.1. Error handling
      If the procedures fail with an unhandled exception (quite likely, as no exception handlers have been set up), the allocated device does not get deallocated. This is unfriendly (the user must exit & restart the session) and will be addressed.