If you run Veeam 7 then you may have seen this screen before in your reports.
Backup location “x:\Backups” is getting low on free disk space
This is because even though your Veeam backup job is running successfully, it has noticed that you have less than 10% of your drive space left – this is the default. If you are doing reverse incremental and have terabytes of storage then we can ignore this message as we still have quite a lot of space free. We should lower the threshold of the Veeam drive warning for how much disk space is free. To do so..
In the example above I have told Veeam to not alert me until there is only 5% of drive space available on the volume. This works for me as I still have 60gb free of drive space and my daily incremental only uses 1gb.