There is bug report https://bugzilla.redhat.com/show_bug.cgi?id=1702316 which describes the same situation, and solution from it works for us. But! It is not clear for me why it is closed as not a bug. There is nothing about it in 6 release notes, so it should work with default values. Just because I can't reopen , I created new bug report. Thank you!
This bug is moved to https://github.com/gluster/glusterfs/issues/844, and will be tracked there from now on. Visit GitHub issues URL for further details