PRODUCT NAME: VAX Distributed File Service, Version 1.2    SPD 28.78.02

DESCRIPTION

The VAX Distributed File Service (DFS) is a DECnet-VAX layered product 
that provides VMS users with the ability to use remote VAX/VMS disks
as if they were directly attached to the local VAX system. 

DFS provides users and applications with transparent, high performance 
file access while using less CPU resources than standard DECnet-VAX file
access.

DFS systems can act as "servers" or "clients" or both.  Servers make file 
resources available to clients.  The resources can vary in scope from a 
master file directory with all of the subordinate directories and 
files on a disk volume to an individual file. The DFS server gives the 
resource a unique name and registers it with the VAX Distributed Name 
Service (DNS).
	 
The DFS client can then use the resource by means of the DFS MOUNT command.  
This command specifies the DNS name by which the resource was registered, 
enables communication between the client and the server, and creates a 
pseudodevice on the client system.  This pseudodevice makes the remote 
resouce appear to the local system like a local disk. Users can then perform 
operations on the pseudodevice, and DFS handles all of the network access 
and translation.

VAX Distributed Name Service is a prerequisite product. In order to use DFS, 
there must be at least one DNS server in the network. DNS allows the name 
of the resource to be independent of its physical location on the network.  
DFS systems throughout the network can continue accessing a resource even 
if the resource location is changed. 

A DFS license is required on each VAX/VMS server node that registers 
available directories or files and on each client node that uses the 
directories or files. 

Features

The features of VAX Distributed File Service software are:

^  High performance access to remote disks

^  Applications require no modifications to use remote
   disks, since the disks appear to be local

^  Uses less CPU resources than standard DECnet-VAX
   file access

^  Supports all VMS file types

^  Supports the following VMS file operations:

   -  Shared access (read)

   -  Exclusive access (read & write)

   -  All VMS Directory operations, including the
      creation and deletion of directories

   -  Virtual I/O

   -  Mapped I/O

^  DFS access is transparent to most of the standard
   VMS DCL commands (those commands which neither
   manipulate identifiers nor use logical, physical or
   write-shared I/O).

^  Uses the VAX Distributed Name Service to provide
   location independence of data.

^  DFS can be used in any DECnet environment. Both
   Local Area Networks and Wide Area Networks are
   supported. DFS is optimized for line speeds of
   56,000 bits per second and above.

^  File security provided through standard VMS
   proxy mechanism. The system manager on the server
   controls all file access.

^  Optional end-to-end checksum provided to guard against
   network faults.

^  Management utility allows the user to control DFS
   components and to display statistical and error
   information.

Restrictions

^  Files opened for write are opened exclusively

^  Logical I/O is not supported

^  Installed files are not supported

HARDWARE REQUIREMENTS

VAX, MicroVAX, or VAXstation configuration as specified in the System 
Support	Addendum (SSA 28.78.01-x)
	
SOFTWARE REQUIREMENTS*
	
At least one DNS server must be installed and accessible in
the DECnet network. See the VAX Distributed Name Service (SPD 
28.79.xx) for further recommendations on DNS. 

VMS or MicroVMS Operating System
	
DECnet-VAX

*Refer to the System Support Addendum for availability and
 required versions of prerequisite/optional software (SSA 28.78.01-x).
	
ORDERING INFORMATION
	
Software Licenses: QL-VEQA*-**
Software Media: QA-VEQA*-**
Software Documentation: QA-VEQAA-GZ
Software Product Services: QT-VEQA*-**
	
*Denotes variant fields. For additional information on available 
 licenses, services and media, refer to the appropriate price book.
	
SOFTWARE LICENSING
    	
This software is furnished under the licensing provisions of DIGITAL's
Standard Terms and Conditions. For more information about 
DIGITAL's licensing terms and policies, contact your local DIGITAL 
office.
		
LICENSE MANAGEMENT FACILITY SUPPORT 
	
This layered product supports the VMS License Management Facility. 

License units for this product are allocated on a CPU-capacity basis.
	
For more information on the License Management Facility, refer to the 
VMS Operating System Software Product Description (SPD 25.01.xx) or the 
VMS Operating System documentation set.
	
For more information on DIGITAL's licensing policies, contact your local
DIGITAL office.
	
SOFTWARE PRODUCT SERVICES
	
A variety of service options are available. For more information on 
these or other services, please contact your local DIGITAL office.

SOFTWARE WARRANTY
	
Warranty for this software product is provided by DIGITAL with the 
purchase of a license for the product as defined in the Software 
Warranty Addendum of this SPD. 

July 1989
BH-KS64B-TE