efs not preserving time

Is this a feature or a bug? C-h v dired-copy-preserve-time RET gives (some blank lines deleted) -------------- cut here ---->8 ---< head `dired-copy-preserve-time' (buffer: *Hyper Apropos*, mode: Hyper-Apropos) Customizable user variable: value: t *If non-nil, Dired preserves the last-modified time in a file copy. (This works on only some systems.) Use `C' with a zero prefix argument to toggle its value. Property-list: custom-requests: nil custom-type: boolean standard-value: (t) ---- 8<------- cut here ----------> tail Yet when I copy files, `dired-do-copy', the target has the present date. Here is part of the from buffer -------------- cut here ---->8 ---< head /anonymous＠gwyn.tux.org:/pub/redhat/updates/4.2/i386: total 77327 * -rw-r--r-- 1 406 406 8344 Oct 27 15:32 nfs-server-clients-2.2beta37-0.i386.rpm * -rw-r--r-- 1 406 406 78020 Oct 27 15:32 nfs-server-2.2beta37-0.i386.rpm drwxr-xr-x 5 406 406 1024 Oct 27 15:32 .. drwxr-xr-x 2 406 406 6144 Oct 27 15:32 . ---- 8<------- cut here ----------> tail and the target buffer -------------- cut here ---->8 ---< head /home/redhat-updates/4.2/i386: total 74387 C -rw-r--r-- 1 jam jam 78020 Oct 29 19:06 nfs-server-2.2beta37-0.i386.rpm drwxrwxr-x 2 root jam 5120 Oct 29 19:05 . C -rw-r--r-- 1 jam jam 8344 Oct 29 19:05 nfs-server-clients-2.2beta37-0.i386.rpm ---- 8<------- cut here ----------> tail why is the modification time not preserved with the copy? jam