Adjusting Filesystem Size for Windows Deduplication in Veeam Backup & Replication

In our recent implementation of Veeam Backup & Replication for one of our customers, we encountered an issue with Windows Deduplication not working as expected. The setup consisted of two servers, one acting as the Veeam backup server and repository, and the second serving as the backup copy destination. Both servers were running Windows Server 2019 Standard.

To utilize Windows Deduplication, we planned to use ReFS and create a logical volume to store the backed-up data. However, we soon realized that the filesystem size needed to be adjusted to accommodate Windows Deduplication. The reason for this is that Windows Deduplication supports filesystems up to 64 TB in size. Due to the use of 24 x 6 TB disks, we had to create two logical volumes to stay within the 64 TB usable capacity limit.

Configuring the Scale-Out Backup Repository

We created one Scale-Out Backup Repository per server and configured our backup jobs. At this point, things took an unexpected turn. The backup ran fine, but as soon as the copy kicked in, the copy job failed with an error message “No scale-out repository extents are available.” This was quite puzzling, as everything seemed to be working correctly.

Troubleshooting the Issue

We tried setting limits (throughput or concurrent tasks) but that did not resolve the issue. To further troubleshoot the problem, we opened a case at Veeam and provided debug logs for analysis. The support team advised us to set a registry key to resolve the issue.

The registry key in question is described in Veeam KB2282, and it was introduced with Backup & Replication 9.5 U2. Our customer was running the v10.0.1.4854 version of Veeam, so we knew the key would be applicable.

The registry key forces Veeam to update free space information with real values and subtracts the estimated sizes of all tasks currently going to the selected extent. This ensures that the backup and copy jobs can complete successfully without running into issues with available space.

Resolving the Issue

After setting the registry key, we restarted the Veeam services, and both the backup and copy jobs ran fine without any further issues. No more error messages or failed jobs. The customer was relieved that the issue was resolved, and their data was being backed up and replicated successfully.

Conclusion

In conclusion, adjusting the filesystem size for Windows Deduplication in Veeam Backup & Replication is a crucial step to ensure successful backup and copy jobs. The registry key solution provided by Veeam support resolved the issue we encountered with “No scale-out repository extents are available” error message. This experience reinforces the importance of proper planning, testing, and troubleshooting when implementing a backup and replication solution.

Remember to always consult the official Veeam documentation and seek support from the vendor if you encounter any issues or have questions about their products. With the right knowledge and tools, you can ensure successful backups and replication for your critical data.