How to recover data from Synology Active Backup

Synology uses its own application for creating backups - Synology Active Backup for Business. You can read about the features of this application on the company's official website, but it should be noted that one of the most useful, yet complicating data recovery processes, features is data deduplication developed by Synology.

Active backup for business

Synology NAS Filesystem

Synology NASes typically use the btrfs file system from the Linux family. The btrfs file system driver has many capabilities, such as copy-on-write, compression, metadata checksums, snapshots, etc. (read more here ), but it does not include deduplication, which is crucial for storing backups as it allows significant space savings. There are third-party projects, such as BEES, that offer deduplication solutions for the btrfs file system, but Synology has developed its own solution.

Synology deduplication

Deduplication Technology

Deduplication is a technology that basically detects and eliminates the superfluous data and only retains unique blocks on the device. This can significantly save disk space, especially for backups with similar data patterns, such as Windows machine backups, where a large portion of file system metadata may contain identical blocks with a high likelihood.

These identical blocks are typically stored in a special pool, and instead of full backup image files, maps with references to such blocks are stored.

Synology Deduplication Features

The main feature of Synology's deduplication technology is that backup image files are not stored on the btrfs file system. This means that data recovery programs that can analyze btrfs metadata will not be able to extract the backup image files themselves. Instead, you will receive small files containing information about changes in specific backup image files, known as delta files, which are useless without the original image file.

At the screenshot below you can find the backup structure as Synology provides it: there is a folder ActiveBackupData which contains original image files and a folder named ActiveBackup with delta files. However, only ActiveBackup folder and its content are stored on the btrfs filesystem while ActiveBackupData is a virtual folder seen only in Synology.

Synology file station Synology delta file

Given all the above, data recovery software like ReclaiMe bring only ActiveBackup folder and delta files.

Synology active backup recovery using ReclaiMe

To extract the backup image files, you will need to perform another recovery on the existing pool of recovered data from the btrfs file system. We, ReclaiMe company, specialize in recovering NASes utilizing Synology Active Backup for Business. If you encounter such a problem, please contact us on the Assistance page.

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