Backup and Recovery for Oracle Databases with Snapshot Feature of

An Oracle White Paper April 2010

Backup and Recovery for Oracle Databases with the Snapshot Feature of Sun Storage 7000 Unified Storage Systems

Oracle White Paper— Backup and Recovery for Oracle Databases with the Snapshot Feature of Sun Storage 7000 Unified Storage Systems

Introduction ......................................................................................... 1 Configuration Details........................................................................... 2

Tested Configurations ..................................................................... 2 Projects and File System Details .................................................... 2 Prerequisites ................................................................................... 3

Using the Snapshot Feature with Oracle Databases .......................... 4 Snapshot Feature Overview............................................................ 4 Cold Backup for Oracle Databases................................................. 4 Hot Backup for Oracle Databases................................................... 6

Accessing the Snapshot, Using the Cloning Process ......................... 8 Clone Overview............................................................................... 8 Cloning the Snapshot...................................................................... 9

Accessing the Clone for Backup ....................................................... 10 Accessing the Clone ..................................................................... 10

Restoration and Recovery of the Oracle Database........................... 11 Rollback Overview ........................................................................ 11 Full Database Restore with the Rollback Feature......................... 11 Restoring and Recovering Datafiles, Using the Rollback Feature ........................................................................... 13 Restoring Only Selected Datafiles ................................................ 15

Recommendations ............................................................................ 15 Conclusion ........................................................................................ 16 Appendix 1: For More Information..................................................... 17


Introduction

Oracle’s Sun Storage 7000 Unified Storage Systems family of products has comprehensive data protection features that provide instant snapshots, cloning, rollback, and remote replication. These features can make database protection and maintenance tasks easier for systems and database administrators. This document shows the methodologies to be used for performing backup and recovery operations on Oracle databases, using the snapshot, clone, and rollback features. It is intended for Oracle Database administrators, system administrators, and anyone else who would like to understand or deploy Oracle databases with these features. Topics covered in this paper include the following:

• Consistent cold backup point-in-time copy using the snapshot feature

• Hot backup point-in-time copy using the snapshot feature

• Using the clone feature for backup, test, and data verification

• Using the rollback feature to restore database files

Note: Because the products in the Sun Storage 7000 Unified Storage Systems family provide the same Web-based graphical user interface, this document applies to the entire family. The release used here was 2008.Q4.

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Configuration Details

The following sections and Figure 1 offer details about the configuration used for the examples discussed in this paper.

Tested Configurations

• Database release:

• Oracle9i Database Release 2 (9.2), Oracle Database 10g Release 2 (10.2), Oracle Database 11g Release 1 (11.1.6)

• Operating system:

• Oracle Solaris 10 5/08 for SPARC and x64 platforms

• Red Hat Enterprise Linux (RHEL) 5.2 (x64) NFS version 3

Projects and File System Details

• Sun Storage 7000 Unified Storage Systems: isv-USS

• Oracle userid in the Sun Storage 7000 Unified Storage Systems: oracle

• Production database details:

• Oracle project: oracle_project

• Oracle Database shares: oradata, oralog, oraarchive

• Control files: Stored in oralog share

• Mount point in the Sun Storage 7000 Unified Storage Systems: /export/oracle_project/<share_name>

• Mount point in the client: /oradata/data, /oradata/logs, /oradata/archive

• Client (database server): isv-6300b

• Cloned database details:

• Cloned Oracle project: oracle_clone_project

• Cloned Oracle Database shares: oradata, oralog, oraarchive

• Cloned mount point in the Sun Storage 7000 Unified Storage Systems: /export/oracle_clone_project/<share_name>

• Cloned mount point in the different client: /oradata/data, /oradata/logs, /oradata/archive

• Client (database server): isv-6300c

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Prerequisites

Following are the prerequisites for the configuration used for the examples discussed in this paper:

• The Oracle Database instance is already running on the database server (client) accessing the Sun Storage 7000 Unified Storage Systems for the database, using the Network File System (NFS) protocol.

• The user, roles, project, and Secure Shell (SSH) are configured as described in the following BigAdmin articles about the Sun Storage 7000 Unified Storage Systems:

• “Deploying Oracle Databases Using NFS on Sun Storage 7000 Unified Storage Systems” www.sun.com/bigadmin/features/articles/7000_oracle_deploy.jsp

• “Deploying Oracle ASM Using iSCSI on Sun Storage 7000 Unified Storage Systems” www.sun.com/bigadmin/features/articles/7000_oracle_iscsi_asm.jsp

Note: The clone is accessed from an alternative client (isv-6300c), and the database server (isv 6300b) accesses oracle_project.

Figure 1. This figure depicts configuration details of the Sun Storage 7000 Unified Storage Systems usage of the snapshot feature.

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Using the Snapshot Feature with Oracle Databases

Sun Storage 7000 Unified Storage Systems products provide a convenient way to take a point-in-time snapshot copy of either the share or the project containing the database files.

Snapshot Feature Overview

Snapshots are read-only copies. In a project-level snapshot, every share in the project has its own copy of the snapshot, all with the same snapshot name. The snapshot uses a copy-on-write method and hence doesn’t occupy any space at the beginning. When new data is written to the share, the old copy is written to the snapshot.

Sun Storage 7000 Unified Storage Systems products can support an unlimited number of snapshots. A snapshot is dependent on the parent share.

Figure 2. Sun Storage 7000 Unified Storage Systems products can support an unlimited number of snapshots.

Types of Snapshots

Sun Storage 7000 Unified Storage Systems products can support the following types of snapshots:

• Manual snapshots. Manual snapshots are on-demand snapshots. The user can initiate a snapshot anytime, at either the project level or the share level.

• Scheduled snapshots. At a predetermined interval defined by the user (minute, hour, day, week, month), snapshots are automatically taken without user interaction. With this method, users have the choice of specifying the number of snapshots kept.

Cold Backup for Oracle Databases

Cold backup is the type of Oracle database backup done when the database is in shutdown (or in not-mounted state). If the database is running in nonarchived log mode, this is the only possible backup mode. The backup time depends on the size of the database and also on how fast the copy is made.

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With the snapshot feature, the downtime of the database can be reduced dramatically, because the database needs to be in shutdown for only a few seconds until the snapshot is taken.

Figure 3. This figure illustrates a snapshot of the database, or cold backup.

To take a consistent snapshot of the Oracle database

1. Shut down the database.

SQL> shutdown immediate;

2. Take the snapshot of the share. From the GUI, select Shares -> Projects -> [oracle_db project] -> Snapshots.

3. Click + to add a manual snapshot, and provide a name such as oracle_snap.

4. Alternatively, steps 2 and 3 can be done with the command-line interface (CLI). From the client (isv-6300b), do this: # ssh -l oracled isv-USS -T <create_snap.ak

# cat create_snap.ak

script EOF

run(‘shares select oracle_db’);

run(‘snapshots snapshot oracle_snap’);

run(‘commit’);

EOF

5. Restart the database.

SQL> STARTUP PFILE=<init param file>;

Here are the scripts for the cold backup (to run as Oracle user):

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• cold_backup.sh

• startdb.sh

• shutdb.sh

Hot Backup for Oracle Databases

In this mode, the backup is done while the database is up and running. With this backup method, the database must be running in archivelog mode. The backup time depends on the size of the database and also on how fast the copy is done. With the snapshot feature, the amount of time the database needs to be in “hot backup” mode is reduced dramatically.

To take a snapshot of the Oracle database in hot backup mode

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1. Place the tablespaces (Oracle9i Database) or the database (Oracle Database 10g, Oracle Database 11g) in hot backup mode. SQL> alter database begin backup;

or

SQL> alter tablespace <tablespace_name> begin backup;

(Repeat step 1 for all the tablespaces.)

2. Take the snapshot of the share. From the GUI, select Shares -> Projects -> [oracle_db project] -> Snapshots.

3. Click + to add a manual snapshot, and provide a name such as oracle_snap. A snapshot of the whole project with all the shares is taken.

4. Alternatively, steps 2 and 3 can be done with the CLI. From the client, do this: # ssh -l oracled isv-USS -T <create_snap.ak

# cat create_snap.ak

script EOF

run(‘shares select oracle_db’);

run(‘snapshots snapshot oracle_snap’);

run(‘commit’);

EOF

5. Take the database out of hot backup mode.

SQL> alter database end backup;

or

SQL> alter tablespace <tablespace_name> end backup;

(Repeat step 5 for all the tablespaces.)

The whole hot backup procedure can be automated with the following script:

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• hot_backup.sh

• begin_hot_backup.sql

• end_hot_backup.sql

Accessing the Snapshot, Using the Cloning Process

Cloning is the process of creating a readable/writable view of the snapshot.

Clone Overview

Cloning can be done only at the share level. More than one clone can exist for a snapshot, and each can have its own mount points, iSCSI target data, and so on. While clones are being used for read/write purposes, snapshots can be taken for those clones. Because a clone is a readable/writable view of the snapshot, there is a dependency between a clone and its parent snapshot. If either the

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snapshot or the parent share/logical unit number (LUN) is deleted, all the children snapshots as well as their clones and the clone snapshots will be deleted.

Cloning the Snapshot

Following is the procedure for cloning a snapshot:

1. If the clones are to be grouped under a different project, create the project: oracle_clone_project

Update the default mount point to

/export/oracle_clone_project

2. From the GUI, go to Shares -> Projects -> [ oracle_project] -> Shares -> [pencil icon for the oradata share that holds the Oracle database] -> Snapshots.

3. Click + on the oracle_snap snapshot.

4. From the Project list, choose the name of the clone, as shown in Figure 4.

Figure 4. This figure depicts the user interface for cloning a snapshot.

5. Repeat steps 1 through 3 for the oralog and oraarchive shares.

6. Alternatively, steps 2 through 5 can be done with the CLI. From the client, do this: # ssh -l oracled isv-USS -T <create_clone.ak

# cat create_clone.ak

script EOF

run(‘shares select oracle_project’);

run(‘select oradata’);

run(‘snapshots select oracle_snap’);

run(‘clone oracle_clone_project oradata’);

run(‘commit’);


run(‘select oralog’);


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run(‘clone oracle_clone_project oralog’);

run(‘commit’);


run(‘select oraarchive’);


run(‘clone oracle_clone_project oraarchive’);

run(‘commit’);

EOF

7. If the original project is chosen, all the project characteristics will be inherited. It will have the mount point /export/oracle_clone_project/.

Accessing the Clone for Backup

The following sections describe the processes for accessing the clone for backup.

Accessing the Clone

Follow these steps to access the clone:

1. From a different client, mount the clone shares as a regular share: # mkdir -p /oradata/data

# mkdir -p /oradata/logs

# mkdir -p /oradata/archive

# chown -fR oracle:dba /oradata

# mount -F nfs isv-USS:/export/oracle_clone_project/oradata /oradata/data



2. If the original snapshot was taken with the cold backup method, the database can be opened for read/write straightaway without the need for recovery.

SQL> startup ;

3. If the snapshot was taken with the hot backup method, the database must be recovered. SQL> startup mount;

SQL> recover automatic database;

SQL> alter database open;

4. Either perform a physical copy of the backup or use third-party backup software to back up the database.

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Restoration and Recovery of the Oracle Database

The following describes the procedures for restoring and recovering the Oracle database.

Rollback Overview

Sun Storage 7000 Unified Storage Systems products provide a convenient way to do faster restoration of the file system or the LUN from the snapshot. It is important to note that the rollback happens at the share level and not with individual files in the share. In other words, the entire share is rolled back.

Full Database Restore with the Rollback Feature

In this scenario, the backup is taken for the whole project. Following is the process for rolling the database back to the point in time when oracle_snap was taken. This process voids all the modifications performed on the database after oracle_snap was done.

Figure 5. This figure illustrates restoring the full database, or full database rollback using cold backup.


2. From the GUI, select Shares -> Projects -> [oracle_project] -> Shares -> [oradata] -> Snapshots.

3. Click the rollback icon, on the line that shows oracle_snap, as shown in Figure 6.

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Figure 6. This figure depicts the user interface for rollback and, specifically, the rollback data icon.

4. Repeat steps 2 and 3 for oralog and oraarchive.

5. You can do steps 2 through 4 by running the script from the client: # ssh isv-USS -T <rollback_snap.ak

# cat rollback_snap.ak

script EOF




run(‘rollback’);

run(‘commit’);


run(‘select oralog’);



run(‘commit’);

run(‘select oraarchive’);



run(‘commit’);

EOF

6. After the rollback is complete, start the database and verify the content.

SQL> startup ;

The following scripts can be used to do the full restore of the database:

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• full_db_restore.sh

• startdb.sh

• shutdb.sh

Restoring and Recovering Datafiles, Using the Rollback Feature

In this mode, only the datafiles are restored. The current control files, online redo logs, and archived logs are necessary to perform the recovery of the datafiles, so only the oradata share should be rolled back. If this share contains a copy of the control file, copy the current control file to oradata after the rollback before attempting recovery.

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Figure 7. This figure illustrates the process for recovering datafiles, or datafile rollback using hot backup/need recovery.


2. From the GUI, select Shares -> Projects -> [oracle_project] -> Shares -> [oradata] -> Snapshots.

3. Click the rollback icon from the line that shows oracle_snap.

4. Alternatively, you can do steps 2 and 3 with the CLI by running this script from the client: # ssh isv-USS -T <rollback_snap.ak

# cat rollback_snap.ak

script EOF





run(‘commit’);

EOF

5. When the rollback is complete, mount the database, perform the recovery, and open the database. SQL>startup mount ;

SQL>recover automatic database;

SQL>alter database open;

Now the database is fully recovered.

The following scripts can be used to carry out the recovery process:

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• db_restore_recover.sh

• startdb_recover.sh

• shutdb.sh

Restoring Only Selected Datafiles

If only selected datafiles from the snapshot need to be restored, the process will be manual.

1. Shut down the database (if necessary). If only a non-system-related datafile needs to be restored, you can offline the datafile only.

2. Follow the process defined to create a clone of the snapshot for oradata.

3. Mount the clone at the client.

4. Copy the specific files from the clone to the original share.

5. Recover the datafile or the full database, depending on which files are restored.

6. Open the database.

7. If the clone is not needed anymore, destroy it.

Recommendations

If the database has many tablespaces and datafiles, the datafiles can be spread across different shares in the same project, for efficient restore/recovery. For example, the payroll user data and index might be

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on an oradata_payroll share, oradata_system might hold SYSTEMS and SYSAUX tablespaces, and so on.

• Periodically perform housekeeping on the clones and snapshots.

• The snapshots and clones are dependent copies. The files have to be copied to the remote location either on tape or on different physical drives to create independent physical copies.

• Take a snapshot of the database (or even a backup) before you perform a rollback operation. Once the rollback is done, the process is irreversible.

Conclusion

Oracle’s Sun Storage 7000 Unified Storage Systems products deliver comprehensive data protection features that make database protection and maintenance tasks easier for systems administrators and database administrators. Instant snapshots, cloning, rollback, and remote replication are all methodologies that can be used for performing backup and recovery operations with Oracle Database. Understanding and utilizing these features will enhance the security of your mission-critical data.

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Appendix 1: For More Information

Here are some additional resources:

• Oracle Technology Network: oracle.com/technology/index.html

• Product documentation: oracle.com/sundocs

• Training: http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=315&p_org_id=1001&lang=US

• Sun Storage Web site: oracle.com/us/products/servers-storage/storage/index.htm

• Support/resources: oracle.com/support

Backup and Recovery for Oracle Databases with the Snapshot Feature of Sun Storage 7000 Unified Storage Systems April 2010 Authors: Sridhar Ranganathan and Jeffrey Wright Oracle Corporation World Headquarters 500 Oracle Parkway Redwood Shores, CA 94065 U.S.A. Worldwide Inquiries: Phone: +1.650.506.7000 Fax: +1.650.506.7200 oracle.com

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