NetVault Plug-in for DB2 3.3

Offline Backups: Offline backups require exclusive connection to the database. Other users and applications cannot connect to the database while the backup is in progress.

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Online Backups: Online backups allow other users and applications to connect to the database, and read and modify the data while the backup is in progress. For online backups, a database must be configured for Archive Logging. For details, see Enabling Archive Logging for the database. During online backups, all database transactions are recorded in the logs. When the backup completes, the database manager closes the active log and archives it. After restoring an online backup, the logs must be rolled forward to recover the database to a consistent state.

Available backup types

Plug‑in for DB2 supports the following backup types:

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Full Backup: A Full Backup includes all the data in the specified database or tablespace. It serves as the base for the subsequent Incremental and Delta Backups.

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Incremental Backup: An Incremental Backup includes any data that has changed or is new since the last Full Backup. Incremental Backups duplicate the data backed up by the previous Incremental or Delta Backups. These backups are also referred to Cumulative Backups.

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Delta Backup: A Delta Backup, or Incremental Delta Backup, includes any data that is new or has changed since the last Full, Incremental, or Delta Backup of the specified tablespace. Delta Backups consume minimum storage space and are quicker to perform. These backups are also referred to Non-Cumulative Backups.

Defining a backup strategy

A backup strategy helps you recover from the damages caused by failure, and resume normal operations as quickly as possible. Before backing up data, ensure that a strategy is in place that safeguards data against various failure modes, such as media failure, data corruption, user error, and loss of a data center.

The following list provides guidelines on some of the backup sequences you might consider using.

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Full Backups Only: When requirements mandate data protection up to the previous day, performing Full Backups daily should be sufficient. If a failure occurs, the plug-in only requires that you restore a single saveset.

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Full Backup and Archived Logs Backup: When requirements mandate data protection up to the current time, but recovery time is not important, Full Backup and Archived Logs Backup should provide the necessary protection. For example, Full Backups can be performed every Sunday, while backups of Archived Logs can be performed Monday through Saturday.

This strategy requires the plug-in to restore and apply each Archived Logs Backup between the last Full Backup and the point-of-failure in succession. This strategy can lead to longer recovery as the week progresses. To speed up restores, you can include Incremental or Delta Backups, which reduces the number of Archived Logs Backup that must be restored.

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Full Backup and Incremental Backup and Archived Logs Backup: When requirements mandate data protection up to the current time, and recovery must be as fast as possible, Full Backup and Incremental Backup and Archived Logs Backup provides the best combination. For example, Full Backups can be performed every Sunday, while Incremental Backups can be performed Monday through Saturday, and backups of Archived Logs can be performed every 5 to 6 hours. Each Incremental Backup includes all changes since the last Full Backup, and the Archived Logs Backup includes the transaction logs since the last Incremental Backup.

This strategy speeds recovery because the plug-in only has to restore the Full Backup, the last Incremental Backup, and the backups of Archived Logs created between the last Incremental Backup and the point-of-failure.

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Full Backup and Delta Backup and Archived Logs Backup: When requirements mandate data protection up to the current time, and backups have to be as fast as possible, then Full Backup and Delta Backup and Archived Logs Backup is an ideal strategy. For example, Full Backups can be performed every Sunday, while Delta Backups can be performed Monday through Saturday, and backups of Archived Logs Backups can be performed every 5 to 6 hours. Each Delta backup includes all the changes since the last Full or Delta Backup, and the Archived Log Backup includes the transaction logs since the last Delta Backup.

This strategy slows recovery because the plug-in must restore the Full Backup, each Delta Backup since the Full Backup, and the backups of Archived Logs created between the last Delta Backup and the point-of-failure.