spec.v1.txt

网络数据管理协议的开发

Network Working Group                                   R. Stager, PDC

Internet Draft                              D. Hitz, Network Appliance
Category: Informational                                   February 1996

                     Network Data Management Protocol


Status of this Memo


     This document is an Internet-Draft.  Internet-Drafts are working
     documents of the Internet Engineering Task Force (IETF), its areas,
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Abstract


     The Network Data Management Protocol (NDMP) addresses the user's need
     for centralized control of enterprise-wide network data management
     while minimizing network traffic. The design objective of the
     protocol is to make every network attached storage device "backup
     ready", enabling true plug-and-play backup operation. The user will
     not be required to install any additional software on an NDMP-
     compliant network storage device. With the NDMP approach, each
     network-attached file server ships with a "universal agent," which
     can be used by any NDMP-compliant backup administration application.
     For IS departments and system administrators, NDMP will ensure
     interoperability between different file servers and backup solutions,
     significantly simplifying the data management process. This same





Internet Draft     Network Data Management Protocol       October 1996


     universal agent architecture is also for network-attached backup
     devices, such as a tape libraries.


Filename:           <draft-stager-pdc-netapp-backup-01.txt>


Expires:            Aug 1997









































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1. OVERVIEW .......................................................5

  1.1 MOTIVATION ..................................................5
  1.2 AUDIENCE ....................................................5
  1.3 TERMINOLOGY .................................................5

2. ARCHITECTURE ...................................................7

  2.1 ARCHITECTURAL MODEL .........................................7
  2.2 COMPARISON ARCHITECTURES ....................................9
  2.3 STATE DESCRIPTION ..........................................11
   2.3.1 Idle State ..............................................13
   2.3.2 Active State ............................................13
   2.3.3 Paused State ............................................13
   2.3.4 Halted State ............................................13
  2.4 PROTOCOL INTERFACES ........................................14
   2.4.1 NDMP Server Interfaces ..................................14
   2.4.2 NDMP Client Interfaces ..................................15
  2.5 MESSAGING PROTOCOL .........................................15
  2.6 HEADER .....................................................16
  2.7 ERROR ......................................................18
  2.8 MESSAGE DEFINITIONS ........................................21

3. NDMP SERVER INTERFACES ........................................24

  3.1 CONNECT INTERFACE ..........................................24
   3.1.1 Open Connection .........................................24
   3.1.2 Authorization ...........................................25
   3.1.3 Close Connection ........................................27
  3.2 CONFIG INTERFACE ...........................................27
   3.2.1 Get Host Info ...........................................27
   3.2.2 Get backup Type Attribute ...............................29
  3.3 SCSI INTERFACE .............................................30
   3.3.1 Open SCSI Device ........................................30
   3.3.2 Close Device ............................................32
   3.3.3 Get SCSI State ..........................................33
   3.3.4 Set SCSI Target .........................................34
   3.3.5 Reset Device ............................................35
   3.3.6 Reset Bus ...............................................36
   3.3.7 Execute CDB .............................................36
  3.4 TAPE INTERFACE .............................................39
   3.4.1 Open Tape Device ........................................39
   3.4.2 Close Device ............................................41
   3.4.3 Get Tape State ..........................................42
   3.4.4 MTIO ....................................................44
   3.4.5 Write ...................................................46
   3.4.6 Read ....................................................48
   3.4.7 Set Record Size .........................................49


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   3.4.8 Execute CDB .............................................50
  3.5 DATA INTERFACE .............................................50
   3.5.1 Get Data State ..........................................50
   3.5.2 Backup ..................................................55
   3.5.3 Recover .................................................58
   3.5.4 Abort ...................................................60
   3.5.5 Stop ....................................................61
   3.5.6 Continue ................................................62
   3.5.7 Get ENV .................................................63

4. NDMP CLIENT INTERFACES ........................................65

  4.1 NOTIFY INTERFACE ...........................................65
   4.1.1 Notify Paused ...........................................65
   4.1.2 Notify Halted ...........................................66
   4.1.3 Notify Connect ..........................................66
  4.2 LOGGING INTERFACE ..........................................68
   4.2.1 Log .....................................................68
   4.2.2 Debug ...................................................68
  4.3 FILE HISTORY INTERFACE .....................................71
   4.3.1 Add Unix Path ...........................................71
   4.3.2 Add Unix Dir ............................................74
   4.3.3 Add Unix Node ...........................................75

5. REFERENCES ....................................................76


6. SECURITY ......................................................76


7. AUTHORS .......................................................76




FIGURE 1. SIMPLE CONFIGURATION ....................................7
FIGURE 2. TWO DRIVE CONFIGURATION .................................8
FIGURE 3. JUKEBOX CONFIGURATION ...................................9
FIGURE 4 - BACKUP STATE DIAGRAM ..................................12














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1. Overview

1.1 Motivation

The purpose of this protocol is to allow a network backup application to
control the backup of an NDMP compliant server using a universal agent
without installing special software on the server.


This separation of control and data allows complete interoperability at a
network level. The file system vendors need only be concerned with
maintaining compatibility with one, well-defined protocol. The backup
vendors can place their primary focus on the sophisticated central backup
administration software.


This protocol is specifically intended to support tape drives. This
protocol is targeted towards backup software and there are extensive
references to the tasks of backup and restore. However, the protocol may
be used for other applications in the future.


1.2 Audience

This document is intended for use by software developers to implement
Network Data Management Protocol. The reader is assumed to be familiar
with network protocol specifications and with the general operation of
backup software.  The user is not expected to have knowledge of internal
backup software behavior.


1.3 Terminology

NDMP client


     The application that controls the NDMP server.


NDMP host


     The host which has a tape drive physically attached and can perform
     local backups to that tape drive using the NDMP.


NDMP server





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     The virtual state machine on the NDMP host that is controlled using
     the NDMP protocol.  There is one of these for each connection to the
     NDMP host.  This term is used independent of implementation.


















































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2. Architecture

2.1 Architectural Model

The architecture is a client server model and backup software is
considered a client to the NDMP server. For every connection between the
client and the NDMP host there is a  virtual state machine on the NDMP
host that is controlled using the NDMP.  This virtual state machine is
referred to as the NDMP server. Each state machine controls at most one
device used to perform backups.  The protocol is a set of XDR encoded
messages that are exchanged over a bi-directional TCP/IP connection and
are used to control and monitor the state of the NDMP server and to
collect detail information about the data that is backed up.


In the most simple configuration, NDMP client will backup the data from
the NDMP host to a tape drive connected to the NDMP host.


                          Network Boundary
                               *
            BACKUP HOST        *        NDMP HOST
                               *
                               *                                                                        
 ____________________          *            ____________________
|  Backup Software   |         *           |    NDMP Server     |
|                    |<--NDMP Connection-->|                    |
|____________________|         *           |____________________|
                               *              ^              |
                               * Backup Data  | Backup data |
                               *       _______|__      _____V___
                               *      |          |    |  Tape   |
                               *      |  Disk    |    |  Drive  |
                               *      |          |    |         |
                               *      |          |    |_________|
                               *      |__________|
                               *
                               *
                          Network Boundary

Figure 1. Simple configuration







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It is also possible to use the NDMP to simultaneously backup to two tape
drives physically attached to the NDMP host.  In this configuration there
are two instances of the NDMP server on the NDMP host.





                Network Boundary
                     *
BACKUP HOST          *       NDMP HOST
                     *
                     *                                                                        
 __________          *            ____________      
| Backup   |         *           |NDMP Server |      
| Software |<--NDMP Connection-->|____________|     ___________
|          |<--NDMP Connection--------------------->| NDMP     |
|__________|         *            ^       |         | Server   |
                     *      Backup| Backup|         |__________|
                     *      Data  | Data  |   Backup ^ Backup|
                     *       _____|_   ___V___ Data  |  Data |
                     *      |       |  |      |      |       |
                     *      |       |  |Tape  |      |       |
                     *      |  Disk |  |Drive |  ____|_   ___V__
                     *      |       |  |      | |      | |      |
                     *      |_______|  |______| |      | |Tape  |
                     *                          |Disk  | |Drive |
                     *                          |      | |      |
                     *                          |______| |______|
                     * 
                     *
                Network Boundary




Figure 2. Two drive configuration


The NDMP can be used to backup data to a tape drive in a jukebox that is
physically attached to the NDMP host. In this configuration, there is a
separate instance of the NDMP server to control the robotic arm  in the
jukebox.
















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                Network Boundary
                     *
BACKUP HOST          *       NDMP HOST
                     *
                     *                                                                        
 __________          *            ____________      ____________
| Backup   |         *           |NDMP Server |    |            |
| Software |<--NDMP Connection-->|____________|----|-> Robotics |
|          |         *            ____________     |   Control  | 
|          |<--NDMP Connection-->| NDMP Server |   |            |
|__________|         *           |_____________|---|-> Tape     |
                     *            ^                |   Drive    |
                     *      Backup|                |            |
                     *      Data  |                |Tape Jukebox|
                     *       _____|___             |____________|
                     *      |         | 
                     *      |         |  
                     *      |  Disk   |  
                     *      |         |  
                     *      |_________|  
                     *  
                     *                       
                Network Boundary







Figure 3. Jukebox configuration


2.2 Comparison Architectures

It is useful to compare the NDMP architecture to other architectures and
note the similarities and differences.


rmt


The architecture is similar to the rmt architecture in that connection is
made to a generic server and the server is instructed to open a specific
tape drive device. The NDMP differs in that it uses a TCP/IP connection to
a dedicated port whereas  rmt uses the rsh  demon to launch a server.


X11


The architecture is similar to the X11 architecture in that it uses a
single connection to a TCP/IP port, however it differs in that the NDMP
server is not assigned to a device until the client opens a device and
that there is only one client per NDMPserver, whereas X11 is assigned to a



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display device before the first client connects and accepts connections
from many clients.


RPC


The NDMP architecture is similar to RPC in that it uses XDR encoding. NDMP
differs in that it is only defined for a TCP/IP connection and that it is
not a call-return model, but rather a bi-directional asynchronous
messaging model.










































Stager,Hitz                                                    Page 10