Arq Backup (currently Version 7.x as of 2026) is the industry standard for "bring-your-own-storage" backups. It is highly efficient, using block-level deduplication and client-side encryption.

Here is how to set up Arq for an SFTP destination on both Windows and macOS.

Phase 1: Adding your SFTP Storage

Before you can back up files, you must tell Arq where the "vault" lives.

1. Open Arq and go to the Storage Locations section (on the left sidebar).
2. Click "Add Storage Location" or the + button.
3. Select SFTP from the list of cloud and protocol options.
4. Enter Connection Details:
   • Hostname/IP: Your server address (e.g., backup.yourserver.com).
   • Port: Usually 22.
   • Path: The folder on the server where Arq should store its data (e.g., /home/user/backups/macbook/).
   • Credentials: Enter your username and either your password or select an SSH Key File (e.g., your id_rsa file).
5. Test Connection: Click Continue. Arq will verify the folder exists and ask to trust the server’s SSH fingerprint.

Phase 2: Creating your Backup Plan

Once the storage is added, you need to create a "Plan" that dictates what to back up and how often.

1. Select "New Backup Plan" from the File menu or the main dashboard.
2. Choose Storage: Select the SFTP location you just created.
3. Encryption (Crucial): * Select "Encrypt backup data."
   • Set a strong Backup Password.

   • Note: This password is never sent to your SFTP server. If you lose this, your data is unrecoverable. Write it down in a password manager.

4. Select Folders: * On Mac: Use the "Add Home Folder" shortcut to capture your Documents, Desktop, and Library.
   • On Windows: Manually select your user folder (C:\Users\Name).
5. Schedule: Set it to Hourly or Daily. Arq is very "quiet" and won't slow down your computer while it runs in the background.

Phase 3: macOS Specific Setup (Full Disk Access)

Because macOS has strict privacy controls, Arq needs explicit permission to see your files (like Mail or Photos).

1. Go to System Settings > Privacy & Security > Full Disk Access.
2. Find Arq and Arq Agent in the list and toggle them ON.
3. If they aren't there, click the + icon and navigate to your Applications folder to add them.
4. Restart Arq to ensure the permissions take effect.

Phase 4: Retention & Maintenance

Since SFTP servers don't always provide automatic cleanup, you should manage your "Budget" to avoid filling up the server.

• Retention Rules: In your Backup Plan settings, go to Retention.
• Recommended Setting: "Keep hourly backups for 24 hours, daily for a month, and weekly for a year."
• Validation: For SFTP, Arq cannot "ask" the server if the files are healthy. Every few months, right-click your backup plan and select "Back up and Validate." Arq will download small chunks of data to ensure the server hasn't corrupted anything.

Summary Checklist for Success

• Firewall: Ensure Port 22 is open on your target server.
• Permissions: Ensure the SFTP user has "Write" permissions to the backup folder.
• Exclude Large Trash: Under the "Exclusions" tab in your plan, exclude the Downloads or Trash folders to save bandwidth.

Is your SFTP server a local NAS (like Synology/QNAP) or a remote VPS? Knowing this can help me suggest the best performance tweaks for your upload speed.