Option 1: Understand Expected Behavior
The Free Space estimation system is intended as a safeguard to prevent extents from becoming full. More information can be found in the Backup File Placement section of the Veeam Backup & Replication User Guide.
Option 2: Disable Estimated Free Space Calculation
In environments where jobs are always running, the actual free space will not be checked because the actual free space value is only captured at the start of a job targeted at the scale-out backup repository while no other jobs actively use the same scale-out backup repository. In such an environment, it becomes necessary to disable the estimated free space calculation feature and force actual free space to be checked each time a job starts.
Enabling the following registry settings will force the Free Space to be checked as each job starts.
Server: Veeam Backup Server
Key: HKLM\SOFTWARE\Veeam\Veeam Backup and Replication\
Value Name: SobrForceExtentSpaceUpdate
Value Type: DWORD
Value Data (Default): 0
- 0 - (Default) Use estimated free space logic.
- 1 - Disables estimated free space logic, forcing extent free space to be updated for each job.
Important: It is strongly recommended to only disable the estimated free space feature in environments where Scale-Out Backup Repositories are configured to use Per-Machine Backup Files, the default for SOBR.