A NAS can be an important backup target, but one box is not a complete recovery strategy. Synology’s guidance starts with 3-2-1—three copies, on two media, one off-site—and extends business protection with isolated or immutable copies and recovery testing.
The extra steps matter because ransomware, theft, fire and administrator mistakes can affect more than live data. A separate copy with different credentials and a controlled connection is harder for the same event to destroy.
Design the policy around recovery. Decide which systems return first, how much data loss is acceptable, where credentials are stored and how often restores are tested. Backup success is not last night’s green tick; it is the ability to recover clean data within the time the business can tolerate.
Source: https://www.synology.com/en-global/dsm/solution/data_backup
