Introduction to the Network Data Management Protocol (NDMP)

Intelligent Network Computing

Introduction to the Network Data Management Protocol

(NDMP

)

The explosion of data generation and storage in recent years has led to the introduction of new technologies for storing and managing this data. One of the online storage architectures that has emerged is Network Attached Storage (NAS), which essentially separates application servers and data, and stores the data on storage devices that perform dedicated file serving tasks. The NAStorage is typically a dedicated, high-performance, high-speed

communicating single-purpose file server. While offering many storage management benefits, the NAStorage presents data backup performance and integrity challenges to organizations that attempt to incorporate NAS into their traditional data protection practices.

NDMP (Network Data Management Protocol) was developed to address those challenges by creating efficient and sound backup methodologies that offer high performance restoration capabilities in NAS environments. The NAStorage backup features present solutions of varying degrees of performance, production impact, restoration capabilities, and preservation of file system integrity. An optimal solution incorporates an appropriate combination of these technologies to achieve an organization's recovery point objectives as well as recovery time objectives.

NDMP addresses a problem caused by the particular nature of NAS devices. These devices are not connected to networks through a central server, so they must have their own operating systems. Because NAS devices are dedicated file servers, they are not intended to host applications such as backup software agents and clients. As a consequence, administrators had to mount every NAS volume by either the Network File System (NFS) or Common Internet File System (CIFS) from a network server that did host a backup software agent. However, this cumbersome method led to an increase in network traffic and a resulting degradation of performance.

By defining a common agent to interface between any NAS device and any backup software program, NDMP minimizes demands on network resources, and enables localized backups and disaster recovery The protocol is being further developed by the Storage Networking Industry Association (SNIA) NDMP Working Group.

What is NDMP?

NDMP is an open-standard protocol for conducting data backups and restoration of heterogeneous

network-attached storage devices. In this way file-system data is copied from the file system to the backup device using a common interface regardless of the platform or device.

Likewise, to control file metadata, common commands pass to and from the backup software, regardless of the software application being used.

The NDMP design goal

The NDMP design addresses the complexities of heterogeneous networks by creating a “common agent” used for centralized backup software and file servers.

NDMP provides a common interface between any backup software application and any network-attached storage device. This enables backup software vendors to support a wide variety of network-attached storage devices without having to redesign their backup software applications. It also enables the NAStorage to work seamlessly with any other NDMP-compliant application. This plug and play approach lets the administrator backup data throughout the enterprise, using a combination of NDMP-compliant network-attached servers, backup devices, and backup software applications.

NDMP and vendor proprietary device-specific code

NDMP provides backup software vendors, such as Veritas, the ability to offer backup and restore capabilities on a NAS device without writing proprietary, device-specific code for NAS devices.

The NDMP (V 4.0) protocol runs (with installed license key) on the NAStorage and includes a set of commands that can be called from any third party application (in our case example “NetBackup” of Veritas) running on another server. All NAStorage devices, from the 8200C till the 8420 models, are NDMP compatible.

How does the NAStorage NDMP module functions?

The NDMP protocol can be thought of as a dedicated application that runs on the NAStorage, waiting for requests from backup software products (in our example we use the “NetBackup” software of Veritas) on different media servers, running different platforms and platform versions, thus, creating a thin layer across a network to make easy data backup and restore operations.

As a media server NDMP reads the data stream and writes it to media or reads from the media and writes a NDMP data stream when the operation is either a backup or restore. All media handling functions, such as split-image issues and robotics controls, are handled by this service category.

The backup software uses NDMP to send requests to the NAStorage, which initiates a backup or restore process. During a backup operation, information about the backed up media is sent from the NAS server to another NAS server.

2) A tape device directly attached onto another NAStorage (NAStorage to NAStorage)

The NAStorage NDMP backup process

The process of backing up a NAStorage, using NDMP, involves the following:

1. The backup software (in this case “NetBackup” of Veritas installed in a PC outside the NAStorage) schedules the

backup and determines when the backup will take place, signaling the NDMP data service.

2. The NDMP data service responds that it is ready to do the backup and provides the NAStorage with the location

on the network where the data will be backed up (IP address).

3. The backup software (installed in the PC) commands the NAStorage to scan for the first available tape drive(s) and requests an available media cartridge and loads it in the drive.

Note: NDMP has a tape interface that allows a NDMP client to perform tasks such as positioning the tape, and reading and writing tape labels.

4. The NAStorage then contacts the data service and gives it the IP address and port of the tape drive (NDMP tape service). After the host and the NAStorage are connected, the backup server is released from the backup session, and then the NDMP host starts transferring the data.

Note: The NDMP data server produces a NDMP data stream that the NDMP tape server writes directly to tape. Controlling this stream of data and control characters manages the format on the tape, no backup software proprietary code is required.

5. After the backup operation is completed, the session between the NDMP data service and tape service ends. The

NAStorage is provided metadata detailing the results of the backup.

The NDMP license key and qualified backup software(s) in use with the NAStorage

Configuring the NDMP storage device using “NetBackup”

(Veritas)

Devices” to start the wizard.

3. Click the “Change” button to configure the NDMP storage device.

5. Click the “New” button to add the NDMP server.

6. Fill in the server name (“banker” is a NAStorage 8400), account and password in the appropriate

fields and click “OK”.

7. After the settings the NDMP server will be shown in the field (as shown below). Click the “Next” button.

9. The storage device (in this case TandbergSuperDLT1) is found. Click now the “Next” button.

11. NetBackup will update the device settings. Click the “Next” button.

Configuring the volume on the tape

1. Click the “Media and Device Management” in the left frame and click the “Configure Volumes” to start the wizard.

3. Select the tape device and click the “Next” button.

Configuration of the NDMP backup policy

1. Click “Policies” under “NetBackup Management” in the left frame and click the “New Policy” icon to create a backup policy.

3. Click the “Next” button.

5. Select the data server.

8. Specify the path with the data. Type the path directly such as /nb/test without clicking the folder icon.

(“nb” is the name of a volume and “test” is the name of a folder)

10. Enable the “Full Backup” check box.

12. Set the “Custom” options and click the “Next” button.

Modifying the NDMP backup policy

Executing the backup policy manually

3. NetBackup will popup a message.