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What are the different topologies of an NDMP protocol and what do they mean?

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Applies to

  • Clustered Data ONTAP 8
  • Data ONTAP 7 and earlier
  • NDMP
     

Answer

When configuring or troubleshooting NDMP issues, the topology (also called the NDMP model) plays a significant role in the configuration of NDMP. The term NDMP Topology or NDMP Model refers to the location and ownership of two objects:

  • Data Volume to be backed up
  • Tape Drive where the backup will be written

There is also the storage controller itself and the Data Management Application (DMA), also known as the Backup Application. The DMA is important because the DMA establishes a control connection to the storage controller and will use the control connection to monitor and control the operation (whether it is a backup or restore).

There are four different topologies (or models) that NDMP can be configured:

  • Direct (also called Local)
  • In-Direct (also called Remote or two-way)
  • 3-way
  • Network Attached (not supported by NetApp and will not be covered)

Direct Topology:

In a Direct model, the controller that owns the volume also has a locally attached (can also be connected through a switch using a SAN) Tape Drive. Here the DMA will create a control connection to the storage controller and create a data connection that is local to the controller. This will allow the controller to back up the local volume to the locally attached Tape Drive.

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In-Direct Topology:

In an In-Direct model, the controller that owns the volume does NOT have any tape drives attached to it. In this scenario, the DMA will create a control connection to the storage controller and create a remote data connection back to itself (the DMA). When the backup begins, the DMA will ingest the backup data from the controller and in-turn write the NDMP backup to a tape drive connected to the DMA.

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3-Way Topology

In a 3-way model, there are multiple storage controllers each owning different resources. The first storage controller will own the data volume that is to be backed up. The second storage controller will own the tape drive that will be used for the backup. Here the DMA will create control connection to BOTH controllers (one connection to control the data volume, and other connection to control the tape drive) and instruct the Storage controllers to create a data connection between themselves. When the backup begins, the data will be read from the first storage controller and be written to the tape drive connected to the second storage controller.
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Additional Information

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