Space issues may occur on the appliance as a result of inaccurate free space calculation.
The appliance's purging subsystem may misjudge the amount of available space on the appliance which can lead to slow or failed backups and insufficient space warnings.
To resolve this issue, upgrade your appliance to version 10.1.
For resolutions to other space issues, customers can review the article titled Error: No more space on device.
A defect can occur where the appliance tries to manage free space within the /backups volume itself instead of managing space to the appropriately configured logical device size (a subset of /backups), resulting in not choosing to purge backups that should be purged normally. This can result in not purging data that should be purged, further exacerbating space issues. This is commonly triggered on appliances that are not using retention settings to manage maximum backup age and run full most of the time, then a large backup occurs of unexpected size resulting in overrunning the logical D2D size with new backup data.
This issue typically self-resolves but in busy units may not. 10.1 resolved this issue.
Note: If you are impacted by this condition, after upgrading to release 10.1, the appliance will properly ID backups that it shoudl have prior already purged per rule and remove them. Some customers may perceive this as a reduction in appliance retention, but these backups should not have been allowed to remain.