Dear All, my program maps several blocks of a file into memory with Bigarray.Array1.map_file for writing. Finally the file handle is closed with Unix.close. On local files system everything works as expected. But if the file is on a network drive, the resulting file is after the close still locked [1] and it contains just zeros. My workaround is, to call Gc.full_major() before the close. Then all remaining bigarrays are finalized (the finalizer calls caml_ba_unmap_file(), see bigarray_stubs.c). Calling Gc.full_major () is somewhat dissatisfying. But I’m not sure how it could be solved more cleanly. I would expect that Unix.close should unmap all remaining views of the file. But Unix.close knows nothing about the bigarray mapping. Maybe a special Bigarray.unmap is the solution. Does anyone has a better idea? Thanks, Christoph Bauer [1] You can’t delete it in the windows explorer. ----------------- Siemens Industry Software GmbH & Co. KG; Anschrift: Franz-Geuer-Str. 10, 50823 Köln; Kommanditgesellschaft: Sitz der Gesellschaft: Köln; Registergericht: Amtsgericht Köln, HRA 28227; Geschäftsführung und persönlich haftender Gesellschafter: Siemens Industry Software Management GmbH; Geschäftsführer: Urban August, Daniel Trebes; Sitz der Gesellschaft: Köln; Registergericht: Amtsgericht Köln, HRB 70858