Symptoms
Provider removed a VPS or hardware node from POA. IP address consumed by the removed host was not released during the host removal, it is still marked as occupied in POA Provider Control Panel.
Cause
Not all background tasks related to the host removal were processed.
Host removal is quite complex procedure, it involves multiple components and parts of POA. While removing host, tasks dependencies are not set up directly, they are implemented by means of task groups. There may be several tasks of different queues related to removal of single host, they all are within the single task group of the HostCleanup class.
Once all tasks' queues related to the group are processed, the group is released and special task cleanupHost is scheduled. It removes information about IP addresses, IP pools, installed packages, services and so on and archive info about the host being removed.
Resolution
Process all tasks in queues related to services on the host.