Troubleshooting Duplicity Backups to FTPGrid

Published {$created} by Carsten Blum

Duplicity is a powerful tool for incremental backups, and when combined with ftpGrid, provides a robust offsite backup solution. However, like any system, issues can arise. This guide addresses common problems encountered when using Duplicity to back up to ftpGrid, outlining potential causes and providing troubleshooting steps. For a detailed walkthrough of setting up Duplicity with ftpGrid, see Duplicity backup to ftpGrid.

Common Issues and Solutions

1. Connection Errors ("Connection Refused", "Timeout")

• Cause: The most frequent cause is a network connectivity problem between the system running Duplicity and edgeN.ftpgrid.com. This could stem from firewall restrictions, DNS resolution failures, or an intermittent network outage. Less likely, but possible, is a temporary issue with the ftpGrid infrastructure.
• Solution:
  • Verify Network Connectivity: Use ping edgeN.ftpgrid.com from the system running Duplicity to check for basic connectivity. If ping fails, investigate network configuration or contact your ISP.
  • Firewall Configuration: Ensure your firewall allows outbound connections to edgeN.ftpgrid.com on port 21 (FTP), 22 (SFTP), or the port specified in your Duplicity configuration.
  • DNS Resolution: Confirm that the system can resolve edgeN.ftpgrid.com to a valid IP address.
  • ftpGrid Status: Check the ftpGrid status page for any reported incidents.
• SFTP vs. FTP: If you're using FTP, consider switching to SFTP. SFTP is significantly more secure and often more reliable due to the underlying SSH tunnel. See ftpGrid features for details on supported protocols.

2. Authentication Errors ("Authentication Required", "Bad Password")

• Cause: Incorrect username or password provided to Duplicity. While password authentication is supported, key-based authentication (SSH keys) is strongly recommended for improved security and reliability.
• Solution:
  • Verify Credentials: Double-check the username and password configured in your Duplicity command or configuration file.
  • Key-Based Authentication: Transition to key-based authentication using SSH keys. See Create SSH keys for SFTP, SCP authentication and Advanced SSH key authentication for SFTP for detailed instructions. Using key-based authentication eliminates the need to store passwords and is much more secure. This method is also more reliable in automated backups.
  • Account Status: Ensure the FTP/SFTP account you're using is active in your ftpGrid account. Account suspensions can occur if quotas are exceeded. See the Dashboard for status information.

3. Permission Denied Errors

• Cause: The user account specified in Duplicity lacks the necessary permissions to write to the designated backup directory on the ftpGrid server.
• Solution:
  • Verify Directory Permissions: Confirm that the user account has write permissions to the backup directory. You can manage user permissions and account details through the ftpGrid Dashboard.
  • Account Quota: Ensure your account has sufficient storage quota. Exceeding your quota will prevent new files from being written.

4. "Files Not Found" or Incomplete Backups

• Cause: This can be caused by several factors including network interruptions during the backup process, or problems with the Duplicity archive itself.
• Solution:
  • Check Network Stability: A stable network connection is essential for reliable backups.
  • Duplicity Archive Integrity: Duplicity employs volume shipping, dividing the backup into multiple parts. If a part is corrupted, the backup can fail or be incomplete. Try verifying the archive after a backup.
  • File System Errors: Check the source file system for errors which could cause Duplicity to fail during its operation.

Key Recommendations

• Use SFTP: Prioritize SFTP over FTP for increased security and reliability.
• Employ Key-Based Authentication: Transition to key-based authentication to eliminate password-related issues.
• Monitor Storage Usage: Regularly monitor your storage usage through the ftpGrid Dashboard to prevent account suspensions. See Historical storage for details.
• Review Logs: Consult the Duplicity logs and the Activity Timeline on ftpGrid for detailed error messages and troubleshooting information.