Re: Need information on NFS

David L. Kashtan (KASHTAN@SRI-IU.ARPA)
Sat 20 Dec 86 10:58:38-PST

>More information about the generality and completeness of these implementations
>would be interesting and useful. Could I do a remote mount from my SUN to
>our VMS machine, for example, and access any VMS file? Can the VMS machine
>get at any Unix file (subject to permissions)? How do permissions work?

I am the person who did the VMS NFS implementation, so I think I am
reasonably qualified to comment on NFS as it relates to non-homogeneous
O/S environments:
  The VMS NFS implementation is a server-only NFS implementation.
  It uses the SUN User-Level UNIX NFS implementation and the 4.3BSD-
  based Eunice (in order to provide the necessary UNIX file-system
  semantics). Without Eunice this would have been a very major
  undertaking. I would most likely have had to re-implement a pretty
  good sized chunk of the Eunice file handling system in order to get
  NFS to work on VMS. So, in reality, the way to get an NFS up on VMS
  is to get VMS to pretend that it is UNIX. This is hardly something one
  would be happy about in a standard for non-homogeneous O/S environments.
  Global UIDs are dealt with by having an "nfs_passwd" file on the VMS
  machine which contains the standard UNIX passwd data for the Global
  UNIX world. Incoming UIDs are mapped to usernames using this information
  and then the usernames are used to get the Eunice (i.e. VMS local) UIDs.
  The reverse is used to generate outgoing UIDs.

  You can indeed do a remote mount of a VMS filesystem from your SUN
  workstation and access any VMS file. The performance is about the same
  as a UNIX machine running the User-Level NFS server (it works but it is
  not adequate as a serious file server). It is quite unrealistic to expect
  a client VMS NFS (the required file system semantics are just not there!).
  About the best you could do is a client VMS NFS for UNIX programs running
  under Eunice (which expect UNIX file system semantics).

  It is my feeling that the Lisp Machine NFILE (and its predecessor QFILE)
  remote file access protocols went much further in dealing with file access
  for MANY different types of operating systems and I am very disappointed
  that nobody even looked at them as examples when thinking about NFS.

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