Shared folders provide file storage and management in DSM with configurable permissions and data protection features, including encryption, WriteOnce, and data checksum.

DSM supports multiple permission layers for shared folders and their contents.

• User and group permissions: Read/Write, Read-only, or No access
• Windows ACL with up to 200 permission entries per file or folder
• Unsupported shared folders: photo, satashare, sdshare, surveillance, and usbshare shared folders
• Advanced shared folder permissions for dual-layer access control
• NFS permissions

• Up to 512 shared folders
• Up to 218 encrypted shared folders
• The recommended number of shared folders may differ by Synology NAS model

• Name length: 1–32 characters, case-insensitive
• Description length: Up to 64 characters
• Cannot contain the following characters: ! " # % & ' ( ) * + , / : ; < = > ? @ [ ] \ ^ ` { } | ~
• Cannot begin with a hyphen (-) or a space, and cannot end with a space
• A dollar sign ($) is allowed only as a suffix to hide the folder in SMB connections
• Cannot use system-reserved names: ., .., global, lost+found, home, printers, usbbackup, etc.

• AES 256-bit encryption
• Passphrase encryption and local key encryption with Key Manager

WriteOnce prevents file modification or deletion based on the configured mode, lock state, and retention period. It is available only on specific Synology NAS models.

• Cannot be disabled once enabled
• Mode: Enterprise mode or Compliance mode (Learn more)
• Lock state: Immutable or Append-only
• Locking method:
• Manual file locking
• Auto Lock: Locks files according to the configured mode after the Auto Lock Timer expires
• Configurable retention periods
• Recycle Bin is not supported for WriteOnce shared folders

• Supports exporting permission reports as CSV files
• Each permission report file can contain up to 500,000 records
• Larger permission reports are split automatically into multiple files

The following features require Btrfs volumes:

• Cloning
• Data checksum
• Shared folder quotas
• WriteOnce