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Druva Documentation

Scenarios when the SQL differential backups get converted to full backups

 

This article applies to:

  • Product edition: Phoenix

Overview

When a differential backup is triggered, the agent requests information about databases that are updated. Phoenix backs up the differential data and creates a snapshot in your storage. During the differential backup, the changed blocks (delta) from MDF & NDF files are backed up, but the entire LDF files are skipped. This document lists multiple scenarios due to which the Differential SQL backups gets converted to Full backups.

Scenarios

Phoenix converts differential backups to full backups, if: 

  • A differential backup of a database for which a full backup is not complete is attempted. 
  • A new database file is added to or deleted from a database since the last backup.
  • A database file is renamed or moved since the last backup.
  • A database was renamed.
  • Inconsistencies between the uploaded database files and its metadata are detected. 
  • The master database was included in the last full backup, and the path or name of the master database files changed since the last full backup.
  • Phoenix cannot obtain details about data change from the Volume Shadow Copy Service.
  • A full backup fails, then the next differential backup will be converted to a full backup.
  • If a full backup is executed by Phoenix MS-SQL agent and the second full backup is been executed by a third-party backup tool or MS SQL server. Then Phoenix agent can convert next differential backup to full backup. 
  • If a database is encountered as shrunk since last full/differential backup, Phoenix converts the subsequent differential backups to full backups. 
  • Phoenix cannot take a differential backup on a secondary node of an availability group. In such a case, Phoenix runs a full backup. 
  • If a database is moved, deleted, or added to a backup set, Phoenix converts the next differential backup for all the affected backup sets to full. 
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