I have configured both windows client and linux server (samba) with zlib compression: compression = zlib But I have transferred a txt file of 100Mb in 40 minutes and the same file compressed with gzip (22Mb) in 14 minutes. So I thing compression is not working. Client log tells: Compression enabled using zlib method and server log: Compression enabled using zlib method How can I verify comression is working? maybe compression is working but it is poor?