Yes, you can add more DCBF-Folders also to other Drives, f.E:
omnidbutil -add_dcdir F:\DCBF\DCBF2 -maxsize 4096 -maxfiles 10000 -spacelow 200
Please also check your other DB-Parts, maybe other parts are also near limit (omnidbutil -info & omnidbutil -extendinfo).