Backing Up and Restoring a Database

The ability to backup and restore a database in TimesTen Classic is essential to protect your data. It is recommended that you perform regular backups to minimize the risk of potential data loss.

Use the ttBackup and ttRestore utilities to perform backup and restore procedures. See ttBackup and ttRestore in Oracle TimesTen In-Memory Database Reference for details. You can only run these utilities to backup and restore a database when:

The first two digits of the version of the utility matches the first two digits of the version of the database and
The platform of the utility matches the platform of the database

See Overview of Release Numbers for information on the format of release number.

Note:

You cannot use these utilities in a client-only environment.

Relevant information in this section include:

Backup Features

Every database backup contains the information needed to restore the database as it existed at the backup point, which is the time the backup began. Restoration of a database from a given backup restores the modifications of all transactions that committed before the backup point.

A backup operation is atomic. If it completes successfully, it produces a backup you can use to restore a database to the state of its backup point. See ttBackup in the Oracle TimesTen In-Memory Database Reference for more information.

Note:

Do not manually change the contents of the backup directory. The addition, removal, or modification of any file in the backup directory, except for modifications made by ttBackup and ttRestore, may compromise the integrity of the backup. In this event, restoration of the database from the backup may not be possible.
Databases containing cache groups can be backed up with the ttBackup utility. However, when restoring such a backup, special consideration is required. The restored data within the cache groups may be out of date or out of sync with the data in the back-end Oracle database. To restore a database that contains cache groups, see Backing Up and Restoring a TimesTen Classic Database with Cache Groups in the Oracle TimesTen In-Memory Database Cache Guide for more information.

Types of Backups

TimesTen Classic supports these types of backups.

Full: A full backup contains the most recent consistent checkpoint file and all the existing transaction log files. This backup saves the entire database. For full backups, ensure you have enough disk space available to hold both the existing backup and the new backup. A full backup can be a stream backup. A stream backup writes the database backup file to stdout.
Incremental: An incremental backup moves the backup point of an existing backup forward in time by augmenting the backup with all the transaction log records created from the most recent incremental or full file incremental-enabled backup. An incremental backup moves the backup point of an existing backup forward in time by augmenting the backup with all of the transaction log records created since its last backup point.

An incremental backup typically completes faster than a full backup, as it has less data to copy. The performance gain of incremental backups over full backups comes at the cost of increased disk usage and longer restoration times. Use incremental backups in concert with full backups to achieve a balance between backup time, disk usage, and restoration time. Incremental backups hold transaction logs, so you should run incremental backups regularly.

Before you can perform an incremental backup, you must enable your backup to allow for incremental backups by running the ttBackup utility with the -fileFullEnable or the -fileIncrOrFull options. In either case, if your backup was not previously enabled for incremental, a full file backup is performed before the backup is enabled for subsequent incremental backups. TimesTen Classic supports the creation of up to eight incremental-enabled backup instances for each database. If you attempt to start a ninth incremental backup, TimesTen Classic returns an error.

If you restore a database from a backup, regardless of whether the backup was enabled or disabled for incremental, the restored database is disabled for incremental backups. To enable incremental backups, you must again run the ttBackup utility with the -fileFullEnable or the -fileIncrOrFull.

A set of files containing backup information for a given database, residing at a given backup path, is known as a backup instance. A given backup instance must be explicitly enabled for incremental backups.

The list of backup types supported by TimesTen Classic are included in this table. See ttBackup in the Oracle TimesTen In-Memory Database Reference for more information:

Backup type	File or stream	Full or incremental	Incremental-enabled	Comment
`fileFull`	File	Full	No	Default
`fileFullEnable`	File	Full	Yes	Full backup and resulting backup enabled with incremental backup
`fileIncremental`	File	Incremental	Yes	Fails if incremental backup is not possible
`fileIncrOrFull`	File	Either	Yes	Performs `fileIncremental` if possible, or `fileFullEnable` otherwise
`streamFull`	Stream	Full	No	Stream backup
`incrementalStop`	None	None	No	Does not perform a backup and disables incremental backups. Prevents transaction logs files from accumulating.

Restoring a Database

Run the ttRestore utility to restore a database backup previously created with the ttBackup utility. See ttRestore in the Oracle TimesTen In-Memory Database Reference for details on this utility.

Note:

You can alternatively use corresponding C functions for ttBackup and ttRestore. See TimesTen Utility API in Oracle TimesTen In-Memory Database C Developer's Guide for more information.

Backup and Restore Examples

You can backup and restore a database to a different directory on the same host. You can also backup and restore a database on a different host of the same platform type.

Examples:

Performing a Simple Backup and Restore

This example backs up the database1 database to the /scratch/backup directory. It then runs ttDestroy to delete the database. (ttRestore returns an error if you try to overwrite an existing database.) Finally, it runs ttRestore to restore the database1 database.

% ttBackup -dir /scratch/backup database1
Backup started ...
Backup complete

% ttDestroy database1

% ttRestore -dir /scratch/backup database1
Restore started ...
Restore complete

Moving a Database to a Different Directory

The TimesTen daemon identifies a database by the full path name of the database checkpoint files. To move a database to a different directory, back up the database using the ttBackup utility, create a new DSN definition that specifies the new database path name, then restore the database into its new location using the ttRestore utility.

This example moves a database from /scratch/old/database1 with a database name database1 to /scratch/new/database1 with database name database1_new, using the /scratch/tmp directory for temporary storage.

Create a temporary directory.
```
% mkdir /scratch/tmp
```
Disconnect applications from the database.

Back up the database to the temporary directory

% ttBackup -dir /scratch/tmp -fname database1 database1
Backup started ...
Backup complete

Unload the database from memory. See "Unload the Database from Memory" for information.
Create a new DSN, named database1_new and set the DataStore attribute to the full database path name of the database and the file name prefix:
```
[database1_new]
DataStore=/scratch/new/database1/database1_new
```

Restore the backup in the new location.

% ttRestore -dir /scratch/tmp -fname database1 database1_new
Restore started ...
Restore complete

Remove the temporary directory.
```
rm -r /scratch/tmp
```
After you confirm the database is operational in the new location, optionally, run the ttDestroy utility to destroy the database in the old location, and then delete the old DSN.

Moving a Database to a Different Host (Same Platform)

You can use the ttBackup and ttRestore utilities to move a database between two hosts that have the same major release of TimesTen Classic, the same CPU architecture, and the same operating system.

To copy a database from one host to another with the same CPU architecture and operating system:

Disconnect applications from the database.

Back up the database on the original host using ttBackup.

%ttBackup -dir /scratch/tmp -fname database1 database1
Backup started ...
Backup complete

Move the backup to the new host.
Create a DSN for the database on the new system. See Creating a DSN on Linux and UNIX for TimesTen Classic in the Oracle TimesTen In-Memory Database Operations Guide for more information.

Restore the backup on the new system using ttRestore.

% ttRestore -dir /scratch/tmp -fname database1 database1_new
Restore started ...
Restore complete

After the database is operational on the new host, you can use the ttDestroy utility to destroy the database on the old host, and you can then delete the old DSN.