This Knowledgebase article provides information about the Exception: Directory cannot be created on Passive server when a drive does not exist on the Passive server.
Identical labeled drives must exist on the Primary and Secondary servers. It is of paramount importance that drive letters under Neverfail Heartbeat protection exist on the passive server. During installation, please ensure that all drives are labeled in an identical fashion on the Primary and Secondary servers.
If a filter is set for a non-existent drive then an exception will be raised stating that the 'Directory cannot be created'. As a direct result of this exception, the filter set may be discarded because of the non-existent drive. Full system checking will abort.
This problem has also be observed in situations where a drive fails or has been removed. During system startup or in mid- operation, the missing drive will cause the exception to be raised.
The behavior is by design, to ensure data integrity on the Passive server because the file system cannot be synchronized due to the missing drive. The passive server should be shutdown and the failed / missing drive should be restored.