As per SPR # JCHN6RMRH5 now is Domino 6.5.6 , 7.0.3 and 8.0 we can use INI parameter DEBUG_TRANSLOG_EXTENTS_PERCENTAGE_FULL to specify how full the transaction logging disk gets before deleting extents
SPR# JCHN6RMRH5 - This fix removes log extents instead of marking them for reuse when the Notes.ini variable "Debug_Translog_Extents_Percentage_Full=x" is set.