SDDC Manager external SFTP backup configuration fails with 'relative path' error when specifying a destination directory containing a Windows drive letter

Products

• VMware vCenter Server

Issue/Introduction

 

• When configuring an external SFTP server for SDDC Manager backups, the directory path validation fails.

• The SDDC Manager UI rejects the Backup Directory path, returning UI error messages such as:

  • Provided directory path E:\SFTP is relative path which is not accepted.

  • Provided directory /e:/SFTP is invalid.

• The external SFTP server is a Windows-based system, and the intended backup directory resides on a secondary drive (e.g., E:\SFTP).

 

Environment

VMware Cloud Foundation (VCF) 9.x

Cause

In VCF 9.x, the SDDC Manager UI and API enforce strict validation rules for the Backup Directory field. The field requires a purely Linux-formatted absolute path (e.g., /backup). The validation logic strictly prohibits the use of backslashes (\) and colons (:).

If the Windows SFTP user's session defaults to the C:\ drive, but the target backup folder is on the E:\ drive, the administrator must use a drive letter mapping (e.g., /e:/SFTP) to reach the target location. However, SDDC Manager will reject this string because it contains a prohibited colon character.

Resolution

To resolve this issue, the administrator must configure a directory junction on the Windows SFTP server. This allows SDDC Manager to use a clean, colon-free path while Windows seamlessly routes the data to the secondary drive.

Step 1: Create a Directory Junction on the Windows SFTP Server

1. Log in to the Windows machine hosting the SFTP server using an Administrator account.

2. Open Command Prompt as an Administrator.

3. Use the mklink /J command to create a directory junction point on the primary drive (e.g., C:\) that points to the target backup folder on the secondary drive (e.g., E:\SFTP).

   • Command Syntax: mklink /J C:\<Junction_Name> <Target_Drive>:\<Target_Folder>

   • Example Execution: mklink /J C:\VCF_Backup E:\SFTP

4. Verify the command output states the junction was successfully created.

Step 2: Update the Backup Directory in SDDC Manager

1. Log in to the SDDC Manager UI.

2. Navigate to the Backup page and select the Site Settings tab.

3. In the Backup Directory field, enter the newly created junction name formatted as a Linux absolute path, omitting the drive letter and colon.

   • Example Entry: /VCF_Backup

4. Ensure all other fields are correct and save the configuration.

5. Click Backup Now to verify the configuration completes with a "Successful" status.

Additional Information

Encryption Passphrase Requirement: If this is the initial backup setup, the Encryption Passphrase field will show as "Not Specified" and throw an error. A new, secure passphrase must be defined by the administrator and stored in a secure password vault. If this passphrase is lost, SDDC Manager backups cannot be decrypted or restored.