Forum Discussion
Backing up Azure Files - High cost Read operations
I have found that Azure Files is unusable for large deployments due to the high cost of backups, especially for deployments with lots of small files. Most backup solutions have a changed block tracking mechanism and filter driver that can quickly determine what has changed between the prior backup. If nothing has changed since the last backup, the job quickly makes this determination and the backup job can take seconds to complete. But with Azure Backup backing up Azure Files, it appears to me that each backup has to enumerate every file and blob before making this determination. I first noticed this when I created a 1TB file share and nothing changed with the files from the prior backup and the job took 12 hours to complete. I then looked at my bill and it was $12 in read operations just for that backup where no files have changed. Azure Files is an awesome product, but securing your backups in a vault using Azure Backup just isn't doable from a price perspective. Does anyone know if there are changes on the horizon to Azure Backup in terms of a more robust change block tracking system?
1 Reply
Yes, at present, Microsoft official documentation confirms the limitation and acknowledges the cost implications. There is no indication of upcoming support for CBT in Azure Files backups. Organizations with large-scale deployments should evaluate alternative strategies such as hybrid backup models or third-party solutions to mitigate costs while maintaining data protection.
https://learn.microsoft.com/en-us/azure/backup/manage-afs-backup
