RAID is not a backup and neither is a snapshot - here is the three-layer protection map for Synology shared folders, in the order to set it up.
Permissions decide who may touch your files. They do nothing about the day the disk dies, the NAS is stolen, or ransomware encrypts a mapped drive from an infected PC. Protection is a separate setup from sharing - and on Synology it takes three layers, each cheap, each aimed at a different accident. This page is the map; set up the first layer today.
Example only - snapshots, the recycle bin and backup are layers, not substitutes for each other.
On Btrfs volumes, the Snapshot Replication package can take scheduled point-in-time snapshots of a shared folder - daily is a sane start - and keep a run of older versions. A folder mangled this morning rolls back to yesterday in minutes, including damage done by an encrypted mapped drive, because snapshots are read only and live outside the folder's own permissions. Limits, honestly: snapshots live on the same NAS and the same disks. They die with the box.
For the everyday "I deleted the wrong file" moment, the shared folder recycle bin is faster than any restore job. It is covered in its own guide in this series - enable it per folder and restrict it to administrators. Think of the bin as the five-second undo, snapshots as the day-level undo, and backup as the building-level undo.
Hyper Backup, built into DSM, copies shared folders - with their permissions - to an external USB drive, another NAS, or a cloud target, on a schedule, with versions. The rules that make it a real backup: at least one copy physically elsewhere, restore tested before you need it, and the backup target not permanently writable from the PCs that use the shares. A backup drive that an infected PC can also encrypt is not a backup, it is a second victim.
The full shared folder setup - creating folders, users and permissions - shown live on a Synology NAS.
▶️ Watch Full VideoRAID protects against one disk failing - the NAS keeps running. It faithfully mirrors deletions, corruption and encryption too, instantly, to both disks. It is an uptime feature, not a data protection feature, which is why snapshots and backup still matter.
A snapshot only stores the blocks that changed since it was taken, so a mostly-static folder costs very little. Busy folders with constant large changes cost more. Set a retention count you can afford, watch it for a month, and adjust - the sin is having no snapshots, not having the perfect number.
One Hyper Backup job, running nightly or weekly, to a USB drive or second location that is not left permanently mounted and writable, plus one practice restore. Everything beyond that is improvement; anything less is hoping.