In the Server edition, Veeam Agent retains the number of latest restore points defined by the user. During every backup job session, Veeam Agent for Microsoft Windows checks if there is any obsolete restore point in the backup chain. If some restore point is obsolete, it is removed from the chain.
When removing obsolete restore points, Veeam Agent for Microsoft Windows does not simply delete backup files from disk. It transforms the backup chain so that the backup chain always contains a full backup file on which subsequent incremental backup files are dependent. To maintain the consistency of the backup chain, Veeam Agent for Microsoft Windows uses the following rotation scheme:
- During every backup job session Veeam Agent for Microsoft Windows adds a backup file to the backup chain and checks if there is an obsolete restore point.
- If an obsolete restore point exists, Veeam Agent for Microsoft Windows transforms the backup chain. As part of this process, it performs the following operations:
- Veeam Agent for Microsoft Windows re-builds the full backup file to include in it data of the incremental backup file that follows the full backup file. To do this, Veeam Agent for Microsoft Windows injects into the full backup file data blocks from the earliest incremental backup file in the chain. This way, a full backup ‘moves’ forward in the backup chain.
- The earliest incremental backup file is removed from the chain as redundant: its data has already been injected into the full backup file, and the full backup file includes data of this incremental backup file.