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Function documentation Informix Data Recovery  Locate the document in its SAP Library structure

Use

Data recovery involves a series of operations that enable you to copy the Informix database data so that, in the event of failure involving data loss, you can restore your system and quickly resume normal working with minimal loss. Failure can range from a corrupt disk drive to a full-scale disaster that destroys your computer site. Although data recovery routinely involves copying data to archives and backups, it also enables you to restore your database, if necessary (that is, to enable you to recover from a problem or failure).

Caution

Data recovery at database level does not replace your routine system backups at operating system level. Make sure that, when you make routine system backups, you include the configuration files essential for data recovery. For more information about these files, see the Informix documentation.

For more information about how data recovery fits into the wider picture of ensuring high availability of your SAP System with the Informix database, see High Availability.

Note

With ON-Bar , the terminology used by Informix changed. The term "storage space" refers to dbspaces and blobspaces. The process of making a copy of the data and control information managed by the Informix server, formerly called an archive, is now called a "storage space backup" or a "whole system backup". For more information, see the Informix documentation.

The term "logical-log file backup" – often shortened to "logical-log backup" or even "log backup" – remains the same.

In summary, backup is the ON-Bar term for all copies of the database taken for recovery purposes.

The following operations constitute data recovery:

An archive is a copy of all or a portion of the data that the Informix database server manages. More precisely, an archive is a copy of one or more dbspaces and any supporting data required to restore them.

Refer to Informix Archive.

An ON-Bar backup is a copy of one or more storage spaces and sometimes also the logical logs that the Informix database server manages. You can restore the backup if necessary.

Refer to Informix Whole-System and Storage-Space Backups.

A logical-log backup is a copy of the transaction data held in the logical-log files, used by the database server to record ongoing database activity between archives. Since the logical-log file is reused, it must be backed up regularly. The term "logical-log file backup" is sometimes shortened to "logical log backup", "log backup", or just "backup".

Refer to Informix Logical-Log Backup.

A restore recreates database data after failure has occurred in which data is damaged. The restore happens in the following phases:
    1. Data from dbspaces ( ON-Archive or ontape ) or storage-spaces ( ON-Bar ) is recreated in the physical restore phase.
    2. Logical log data is recreated in the logical restore phase.

Refer to Informix Restore.

You can perform all the operations mentioned above with the data recovery tools supplied by Informix, that is, ontape , ON-Archive , and ON-Bar . However, there are differences in what these tools can do. Refer to Comparison of ontape, ON-Archive, and ON-Bar for Data Recovery.

The following diagram summarizes the major data recovery operations:

This graphic is explained in the accompanying text

 

See also:

ON-Bar for Data Recovery

ON-Archive for Data Recovery

ontape for Data Recovery

Database Backup (ON-Bar)

Archive (ON-Archive and ontape)

Logical-Log Backup

Restore

Informix documentation at http://www.informix.com