Overview

This topic provides basic information about the NDMP protocol used by the DXi Application Specific Path to Tape, PTT, functionality to communicate commands to the DXi.  Understanding the NDMP protocol is useful when configuring PTT on the DXi and the Application and when navigating the activity in the DXi and Application logs.

NDMP Defined

NDMP (Network Data Management Protocol) is an open protocol used to control backup and recovery communications between primary and secondary storage in a heterogeneous network environment.  NDMP specifies a common architecture for the backup of network file servers and enables the creation of a common agent that a centralized program can use to back up data on file servers running on different platforms.  By seperating the data path from the control path, NDMP minimizes demands on network resources.  The DXi Application Specific Path to Tape implementation allows the Backup Application to communicate to the DXi using the control path to identify data to be moved from virtual to physical tape, the write to physical tape is done over the DXi FC connection to the physical tape library significantly mimimizing the use of the Customer network resources for this activity.

Currently, an NDMP server can be thought of providing two services:

• Data server - This service either reads from disk and produces an NDMP data stream (in a specified format), or reads an NDMP data stream and writes to disk, depending upon whether a backup or restore is taking place. 

• Tape server - This service either reads an NDMP data stream and writes it to tape, or reads from tape and writes an NDMP data stream, depending upon whether a backup or restore is taking place. All tape-handling functions, such as split-image issues, are dealt with by this service.

The DXi system has an embedded tape server that takes a NDMP control session from NBU and moves VTL data to physical tape. Quantum's term for this process is Path to Tape (PTT), but the technology is actually referred to as NDMP Direct Copy. 

What's Next?

Configuration Issues >