How to Resolve CIFS Backup Permission Errors and Remote Transport Issues in cPanel & WHM

How to Resolve CIFS-mounted Backup Drive Permissions Errors

Valid for versions 82 through the latest version

Last modified: July 12, 2022

Overview

When performing a backup to a CIFS-mounted drive, you may encounter errors such as:

/bin/cp: failed to preserve ownership: Permission denied

These errors typically occur when the CIFS-mounted drive does not support extended attributes.

Resolve the Error

1. Edit the /etc/fstab file and add the user_xattr option to the CIFS mount entry. Example:

//192.0.2.0/mybackup /backup cifs user,uid=500,rw,suid,credentials=/root/.cifs,user_xattr 0 0

• The local user owns the mounted files.
• The CIFS credentials are stored in /root/.cifs.

Important: Always store CIFS credentials in a secure file.

2. Remount the CIFS drive:

mount -o remount /backup

3. Verify extended attribute support:

lsattr /backup

Warning: If you see “Inappropriate ioctl for device,” the mount does not support extended attributes and cannot be used for cPanel backups.

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How to Run Backups on Locally-Mounted Remote Filesystems

Last modified: July 14, 2025

Overview

To mount or unmount a partition, it must be listed in /etc/fstab. The backup utility only mounts partitions defined in this file.

Warning:

• Backing up directly to remote filesystems (NFS, CIFS, smbfs, etc.) is not recommended.
• cPanel & WHM does not officially support this configuration.
• Work with a qualified system administrator to avoid data loss.

Configure the Filesystem

We strongly recommend mounting the backup filesystem with the noexec option:

/dev/sda5 /backup ext3 defaults,noexec 0 0

Remount the Backup Disk

mount -o remount,noexec /backup

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How to Troubleshoot a Remote Transport Pruning Failure

Last modified: January 28, 2026

Overview

Remote backup pruning may fail if the process exceeds the 300‑second timeout limit. This section explains how to diagnose and resolve pruning failures.

Warnings:

• Your FTP server must support MLSD or LIST commands.
• Hidden files (dotfiles) must have write permissions.
• Pure‑FTPd and ProFTPD are recommended for remote FTP servers.

Transport Error

When a transport error occurs, the system sends an email containing a preview and a full log. Example:

The system could not prune the "home/username/backups/2018-05-24" directory due to an error.

Troubleshooting

1. The Directory Is Too Large

• Manually delete the directory:

rm -rf home/username/backups/2018-05-24

• Disable the user’s backup in WHM:

WHM » Home » Backup » Backup User Selection

• Change backup type from incremental to compressed.

Note: rsync does not support compressed backups.

2. The Backup Drive Is Too Slow

Replace the remote destination with a faster storage system.

3. Network Error

Run the backup again after the network stabilizes:

/usr/local/cpanel/bin/backup

4. Permission Denied

This occurs when:

• A non‑root user connects to an rsync destination.
• Files without write permissions exist in the user’s directory.

Fix by deleting the files or granting write permissions:

chmod +w file

Conclusion

By properly configuring CIFS mounts, managing remote filesystems, and troubleshooting pruning failures, administrators can ensure stable and reliable backup operations in cPanel & WHM.