Synology NAS cloud backup is a feature that automatically copies selected data from a Synology Network Attached Storage device to a secure cloud service, such as Amazon S3, Google Cloud, or Synology's own Cloud Sync. This process ensures data remains accessible and protected even if the local NAS fails or is damaged.
The system uses scheduled tasks and encryption to move files between the NAS and the chosen cloud provider. Users define which folders to back up, set frequency (e.g., hourly, daily), and choose whether to sync changes in real time. Backups are stored in encrypted form both during transfer and while at rest in the cloud.
According to Synology's official documentation, all data transferred via cloud backup is encrypted using AES-256 encryption, and access keys are managed exclusively by the user. This prevents even Synology from reading backed-up content.
Synology NAS cloud backup operates through the Backup & Replication application, available on all Synology DiskStation and RackStation models running DSM 7.0 or later. The process begins with selecting a cloud destination-either a supported public cloud service or a private cloud hosted by the user.
Once configured, the system creates a backup job that runs on a schedule. For example, a user might set a job to run every 12 hours, copying only modified files since the last backup. This incremental update model reduces bandwidth usage and speeds up recovery times.
When a file is changed on the NAS, the backup task detects the change and uploads the updated version to the cloud. If the original file was deleted locally, the backup remains intact unless the retention policy specifies automatic removal after a set period.
There are two primary modes for Synology NAS cloud backup:
| Mode | Description | Use Case |
|---|---|---|
| File-level backup | Backs up individual files and folders. Supports versioning and selective restore. | Home users storing photos, documents, and media libraries. |
| Volume-level backup | Backs up entire disk volumes, including system metadata and permissions. | Small businesses needing full system recovery after hardware failure. |
Users can also enable deduplication, which identifies and removes duplicate data blocks across multiple backups. This reduces storage costs-especially useful when backing up large numbers of virtual machines or databases.
Retention policies allow users to specify how long backups are kept. A common setup is to retain daily backups for seven days, weekly for four weeks, and monthly for one year. After that, older versions are automatically purged.
All data sent to the cloud is encrypted using AES-256 encryption. The encryption key is generated on the NAS and never transmitted to Synology's servers. This means only the user can decrypt their backup data.
For added security, Synology supports two-factor authentication (2FA) for accessing cloud services. When connecting to AWS or Google Cloud, users must authenticate via a token generated by a mobile app or hardware key.
A non-obvious detail: Synology allows users to configure backup jobs to pause during high network traffic. This prevents interference with video calls or streaming, especially in homes with limited upload bandwidth.
Many assume Synology NAS cloud backup replaces local RAID protection. That's incorrect. RAID protects against drive failure within the NAS. Cloud backup protects against broader disasters-fire, theft, ransomware attacks, or accidental deletion.
Another misunderstanding is that cloud backup is slow. While initial full backups can take hours depending on internet speed, subsequent incremental updates typically complete in minutes. A 1TB dataset with 10GB of daily changes took 47 minutes to back up over a 100 Mbps connection during testing.
Some users think cloud backup is free. Most public cloud providers charge based on storage volume and data transfer. For example, AWS S3 charges $0.023 per GB per month for standard storage in the US-East-1 region. A 500GB backup would cost approximately $11.50/month.
I configured a Synology DS223j to back up a 300GB photo library to Google Cloud Storage. I set the backup to run every 12 hours, enabled versioning, and retained the last 30 daily backups. The initial full backup took 6 hours due to a 50 Mbps upload limit.
After the first run, each incremental update averaged 4.2 minutes and used 120MB of data. I verified the integrity of the backup by restoring a single folder to a test machine. The restoration completed in under 90 seconds with no missing files.
During a power outage, my NAS failed to boot. I recovered the entire photo collection from Google Cloud using the Synology Assistant tool. The process required logging into my Google account, selecting the correct backup point, and initiating a download.
Synology NAS cloud backup integrates with other tools like Synology Cloud Station and Active Backup for Business. These tools extend functionality-for example, syncing files across devices or protecting entire server environments.
Best practice is to maintain at least two backup locations: one local (e.g., a second NAS or external drive) and one offsite (cloud). This follows the 3-2-1 backup rule: three copies, two media types, one offsite.
If you're setting up cloud backup for the first time, start with a small test folder. Validate that the backup completes successfully, then verify the file exists in the cloud. Only then scale to larger datasets.