The NDMP protocol and alternatives for filer backup

Freeway

Article from ADMIN 10/2012

By Jens-Christoph Brendel

NAS filers are typically closed systems that prevent users from installing anything – including a simple backup agent. But what happens if you need a backup?

However you do it, when you back up a server, you need to run some kind of software on the system that sends data directly to a medium or to a centralized backup server. Preconfigured servers – including NAS filers – typically prevent the user from installing any kind of additional software. This makes it difficult for the administrator to enforce a backup solution.

One approach is to use the backup agent provided by the NAS vendor. Some NAS systems come with a backup utility; however, this approach binds you to whatever backup solution the vendor decides to include. Even integrated agents could never hope to cover the scope of backup applications available on the market.

Another solution to this problem could be to mount the volume you want to back up on a backup server and then run an agent, but this approach has its downside. For example, all the data in the backup needs to cross the network wire to the backup server, and if you don't have a dedicated connection, impairments are guaranteed because of the sheer volume of data. Also, you might be infringing on security policies by mounting volumes on a server.

To cut this Gordian knot, 1996 Intelliguard (later acquired by Legato, which in turn belongs to EMC today) and Network Appliance (NetApp) joined forces to develop the Network Data Management (NDMP) protocol. The NDMP standard enables protocol-compliant data servers that read from or write to disks to send a data stream to a tape server, which manages the backup medium.

Today, many storage systems by NetApp, HP, EMC, and others understand the protocol: The NDMP website [1] lists a dozen or more vendors of NDMP-compatible backup software, including major players such as IBM, EMC, HP, Symantec, CA, or Fujitsu-Siemens. The NDMP module in the backup program thus is a standardized counterpart for the disk array and the tape library with which it can communicate directly. It is the

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