MaxBack Backup Process
This page explains how MaxBack handles the VSS backup workflow and how to manage transaction log files with your backups.
How VSS backup works
VSS (Volume Shadow Copy Service) is a Windows feature for creating consistent backups. When your backup tool starts a VSS backup, the following events are processed by the MaxBack VSS Writer:
Prepare Backup — The VSS Writer analyzes the database state and verifies if the backup includes the database files. If they are included, the writer requests to participate in the backup.
Prepare Snapshot — If enabled, the VSS Writer executes a log file backup to include it in the snapshot. The database is then checked — if it is online, it is set into a consistent state using the external backup feature of MaxDB.
MaxDB Version
The external backup function is available since MaxDB 7.8.2. See SAP note 1928060 for details.
Freeze — The VSS Writer writes recovery detection information to the file system. This is used by the Autorecovery feature to detect bare metal or VM restores. The database is already in a consistent state at this point.
Snapshot creation — The Windows VSS service creates a snapshot of the volumes included in the backup.
Thaw — The VSS Writer removes the recovery detection information.
Backup completed — When the backup completes successfully, the VSS Writer:
- Confirms the backup in the MaxDB backup history
- Truncates log files (if log truncation is enabled)
- Writes any logs created during the backup operation to the file system
Learn More
A detailed explanation of the VSS service can be found in the Wikipedia article on Shadow Copy.
Simple Log Management
MaxBack can include transaction log files in your database backups and manage their lifecycle automatically.
Log Media Setup
Your log backup media must be defined as a file backup. The target folder should be on a disk included in the backup. It is recommended to use a separate disk for log backups — this allows you to recover logs as a complete volume from a second backup, and to schedule additional log-only backups.
Manual Restore
Log files are not restored automatically. You have to restore them manually using the backup that contains them. For recovery, use the MaxDB command line or the Database Studio.
Log Backup before Snapshot
Writes log files from the database to a local volume before the VSS snapshot is taken. The backup will then contain both the current database state and the log files needed for point-in-time recovery between this and the previous backup.
Activated with the option LogSettings:BackupBeforeSnapshot. See Configuration.
Log Backup after database backup
Executes a log backup automatically after the database backup completes. This is useful for SAP system maintenance without using MaxDB backup tools, since SAP tools check for both a database and a log backup.
Recommendation
Do not use this feature if your backup tool can select database component logs. Instead, create a separate backup definition for log backups only.
Activated with the option LogSettings:BackupOnBackupComplete. See Configuration.
Log truncation
Deletes log files after a successful VSS backup. Only considers files stored on the local filesystem.
Activated with the option LogSettings:TruncateOnBackupComplete. See Configuration.