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.
PHP code:
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 customers 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
PHP code:
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 customers 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
PHP code:
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 customers 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
PHP code:
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 customers 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 .. 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 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.
PHP code:
.
+- 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
