Hi, when a lot of documents are inserted then deleted from a database the compaction can be done but disk space in use is not freed back to OS. The repairDatabase always require a lot of free space on disk to work, even if the size of remaining documents and indexes is a fraction of initial files sizes. repairDatabase or equivalent should be able to require free disk space to proceed using the size of remaining data and not the one of current data files.
Regards.