Option 1: Understand Expected Behavior
The estimated free space system is intended as a safeguard to prevent concurrently running jobs from filling the Scale-Out Backup Repository extents.
More information can be found in the Backup File Placement section of the Veeam Backup & Replication User Guide.
Option 2: Alternate Estimated Free Space Calculation
Since the actual free space is only retrieved when no active tasks are assigned to an extent, in environments where tasks are always running, the estimated free space may begin to deviate from the actual free space over a long enough time. This deviation is due to the slight differences between the estimated size and the actual size of restore points.
The software can be configured to recalculate the extent's estimated free space when a task starts and is assigned to that extent. (The recalculation can only occur if it has been more than 15 minutes since the last estimated free space recalculation.) The recalculated 'estimated free space' will be based on the actual free space minus the estimated restore point size of all active tasks for the extent.
To enable this alternate method of estimating free space, create the following registry value:
Server: Veeam Backup Server
Key: HKLM\SOFTWARE\Veeam\Veeam Backup and Replication\
Value Name: SobrForceExtentSpaceUpdate
Value Type: DWORD
Value Data: 1
- 1 - Enable Alternate Estimated Free Space Calculation using periodic recalculation of free space while tasks are active.
- 0 - (Default) Only retrieve actual free space when no active tasks are assigned to an extent.