SMB / CIFS

Store backups on a Windows share, NAS, or any SMB/CIFS-compatible network storage.

Configuration

Credential Profile required

SMB requires a Credential Profile of type USERNAME_PASSWORD. Create one in Vault → Credentials before saving the destination. For anonymous access, the credential profile username defaults to guest with no password.

Field	Description	Default	Required
Name	Friendly name for this destination	-	✅
Address	UNC share path (e.g. //server/share)	-	✅
Login	USERNAME_PASSWORD credential profile (username + password)	-	❌
Domain	Windows domain / workgroup	-	❌
Highest SMB version	Highest SMB protocol version to use	SMB3	❌
Folder	Subfolder within the share. The folder button beside it browses the share once the connection and its login are filled in	-	❌

Protocol Versions

Protocol	Notes
SMB3	Default, recommended - encrypted transport
SMB2	Fallback for older NAS devices
NT1	SMB1 legacy - use only if required

Setup Guide

1. Create a USERNAME_PASSWORD credential profile in Vault → Credentials (guide)
2. Ensure the SMB share is accessible from the DBackup server
3. Create a dedicated user with write access to the share (recommended)
4. Go to Connections → Destinations → New destination → SMB / CIFS
5. Enter the Address in UNC format: //hostname-or-ip/sharename
6. Pick the credential profile under Login (or leave empty for anonymous access)
7. (Optional) Set Domain if authenticating against a Windows domain
8. (Optional) Set a Folder in the Location part for a subfolder within the share, or pick it with the folder button (📂)
9. Click Test connection to verify the connection

NAS Devices

Synology, QNAP, TrueNAS, and OpenMediaVault all support SMB shares. Create a dedicated share and user for backups in your NAS admin panel.

How It Works

• DBackup mounts the SMB share temporarily for each operation, then unmounts
• Files are written directly to the share - same behavior as local storage
• All credentials are stored AES-256-GCM encrypted in the database
• smbclient must be available in the DBackup container (included in the default Docker image)

Shadow copies (VSS)

Available when the SMB adapter is a directory source. Backing up a live share means reading a tree that keeps changing: open files cannot be read, and files collected at the start and at the end of a long run do not belong to the same moment. For media or documents that rarely matters; for a share holding a running application - a file-based database, PST files, VM images - it produces a backup that does not restore cleanly.

With the option on, DBackup asks the file server for a point-in-time snapshot (MS-FSRVP, the same mechanism Synology Active Backup uses), reads the backup from that snapshot, and releases it afterwards. No agent is installed on the server.

Requirements

Requirement	Note
Windows Server 2012 or newer	Or Samba 4.2+ configured as an FSRVP server
File Server VSS Agent Service	A role service, not installed by default
An account with backup privileges	Plain read access on the share is not enough
RPC reachable through the firewall	The request does not travel over the SMB share itself

Enabling it

The switch stays disabled until Check availability succeeds - the server is asked directly, so a missing agent service or insufficient rights shows up while configuring rather than during the first backup. The same check runs again when the adapter is saved, so it cannot be bypassed through the API.

A job configured for shadow copies fails without one

If snapshots turn out to be unavailable at backup time - the agent service stopped, rights revoked, the server replaced - the run fails instead of quietly backing up the live share. A backup that claims point-in-time consistency and does not have it is worse than a missing one, and the job's failure notification tells you about it.

Cleanup

The snapshot is released when the run ends, whether it succeeded, failed or was cancelled. Should DBackup be killed outright, the leftover is detected and removed before the next backup of that share - which matters, because the server refuses a new snapshot while an old one is still open. vssadmin list shadows on the server shows what is currently held.

Troubleshooting

Connection Refused

NT_STATUS_CONNECTION_REFUSED

Solution: Verify the server address and that SMB is enabled. Check the firewall allows port 445.

Access Denied

NT_STATUS_ACCESS_DENIED

Solution: Check username, password, and domain. Ensure the user has write permission on the share. For guest access, ensure the share allows anonymous connections.

Protocol Negotiation Failed

NT_STATUS_INVALID_NETWORK_RESPONSE

Solution: Try lowering Highest SMB version to SMB2 or NT1. Some older NAS firmware doesn't support SMB3.

Share Not Found

NT_STATUS_BAD_NETWORK_NAME

Solution: Verify the share name is correct. List available shares: smbclient -L //server -U username.

Next Steps

• Enable Encryption
• Configure Retention
• Backups