Backup and Restore

Use the ON–Bar or ontape utility to back up your database server data and logical logs as insurance against lost or corrupted data. A program error or disk failure can cause data loss or corruption. If a dbspace, an entire disk, or the database server goes down, use ON–Bar or ontape to restore the data from the backup copy. You must use the same utility for both the backup and restore.

The following are basic backup and restore terms:

• A backup is a copy of one or more storage spaces and the logical logs.
• A logical-log backup is a copy to tape or disk of logical-log files that have become full and eligible for backup.

  The logical-log files store a record of database server activity that occurs between backups.

• A restore re-creates data from a backup.
• A point-in-time restore allows you to restore the data in a database to a specific time.

  A point-in-time restore can undo mistakes, such as dropping a table, that might not be fixable otherwise.

ontape Utility

The ontape utility does not require a storage manager. Use ontape to perform the following tasks:

• Back up and restore storage spaces and logical logs.
• Change database-logging status.
• Start continuous logical-log backups.
• Use data replication.
• Rename chunks to different pathnames and offsets.

ON-Bar Utility

The ON–Bar utility requires a storage manager such as IBM Informix Storage Manager (ISM). Use ON–Bar to perform the following tasks:

• Back up and restore storage spaces and logical logs.
• Perform point-in-time restores.
• Start continuous logical-log backups.
• Verify a backup with the archecker utility.
• Perform external backups and restores.

  An external backup and restore allows you to copy and physically restore data without using ON–Bar. Then you use ON–Bar for the logical restore.

• Rename chunks to different pathnames and offsets.

For information about backing up data with ON–Bar or ontape and the archecker utility, see the IBM Informix Backup and Restore Guide.

IBM Informix Storage Manager

IBM Informix Storage Manager (ISM) manages data storage for the Informix database server. ISM resides on the same computer as ON–Bar and the database server.

ISM receives backup and restore requests from ON–Bar and directs data to and from storage volumes that are mounted on storage devices. ISM tracks backed-up data through a data life cycle that the database or system administrator determines and also manages storage devices and storage volumes.

For information about ISM, see the IBM Informix Storage Manager Administrator's Guide.

The archecker Utility

When you use the onbar -v command to verify ON–Bar backups, it calls the archecker utility.