25 May 2023

Jason Kent, director, Open Seas

This is especially true in a hybrid working environment where you may have users complain that their file edits are lost after another user elsewhere makes changes to their copy of the same file. Or the amount of users and data being processed on your network is causing bandwidth issues. As a system admin, you may also not be alerted when things go wrong, creating a mess with your file infrastructure.

What is DFS-R?

Distributed File System Replication (DFS-R) is a technology that allows organisations to keep files and folders in sync across multiple servers. It is a free tool that comes as standard with Windows Server operating systems. It was designed to replicate data between DFS Namespaces (another Microsoft tool that creates a virtual file system of folder shares).

The DFS-R service provides basic replication functionality on your network. It can help ensure that data is available and accessible to users across the organisation, even in the event of server failures or other issues. However, DFS-R can be quite costly in terms of ongoing management time and has historically not always been that unreliable, especially on larger file sets.

Troubleshooting slow DFS-R replication

One of the most common issues with DFS-R is slow replication speed. DFS-R can throttle bandwidth usage based on a per connection basis with a fixed throttle. This means that if your bandwidth usage increases, DFS-R does not perform ‘bandwidth sensing’ to adapt the throttling based on changing network conditions.

To resolve this issue, you can consider increasing the bandwidth of your network, upgrading your hardware, or reducing the amount of data being replicated. For example, a Quality of Service (QoS) style throttle helps to avoid slowing your systems down for your users. Even better, a system with advanced, dynamic throttling is best for enterprise-sized systems. This way, the bandwidth usage is based on a percentage of bandwidth available. For instance, you could use 50% of the connection - if the connection is 10Mbps, 50% of the idle connection would be approximately 5Mbps used. If another process consumed 5Mbps of that connection, the throttle would reduce to approximately 2.5Mbps (50% of the free 5Mbps). This allows your file synchronisation system to use more bandwidth when it is available and less when other processes need the bandwidth.

Managing replication consistency

DFS-R may sometimes fail to replicate files and folders consistently across all servers. This can be due to network latency or conflicts between files. To address this issue, you can try increasing the replication schedule, checking for conflicts between files, or running the DFS-R diagnostic report to identify any issues. You can also try implementing a more robust file locking mechanism to prevent simultaneous modifications or configuring DFS-R to use conflict resolution.

Mitigating the impact of file conflicts and deletions

DFS-R may sometimes encounter file conflicts or deletions, which can cause data loss or corruption. This can be caused by synchronisation errors, or by users modifying files simultaneously. To prevent this issue, you can configure DFS-R to use conflict resolution or implement file locking mechanisms to prevent simultaneous modifications. However, Microsoft recommends to not use DFS-R in an environment where multiple users could update or modify the same files simultaneously on different servers.

For environments with multiple users scattered around different locations and servers, engineers need a solution that minimises the ‘multiple updates’ issue. One method may not suit all needs for large enterprises. That’s why it’s best to look for solutions that offer collaborative file sharing between offices and with file locking and a combination of one-way and multi-way rule methods.

DFS-R can work well for some organisations with careful planning and management to ensure that it functions correctly. However, for most large enterprises it is not enough. After all, DFS-R provides limited reporting options, limited ability to synchronise encrypted files, and no ability to synchronise files stored on FAT or ReFS volumes, making it challenging to operate efficiently in today's hybrid workplace. IT staff must adapt systems for users working from different locations while also managing varying bandwidth speeds at different times. IT staff must evaluate their file synchronisation and replication systems and determine if alternative solutions are required to meet their organisation's needs.

By addressing these common issues and implementing the appropriate solutions, you can help ensure that your DFS-R implementation runs smoothly and reliably. In addition, by understanding the risks associated with synchronisation, you can take steps to mitigate those risks and protect your data. By following best practices and staying up to date with the latest developments in DFS-R technology, you can help ensure that your organisation is able to take full advantage of the benefits of Distributed File System Replication and DFS Namespace.