NDMP specifies a common architecture and data format for backups and restores of NAS. With NDMP, heterogeneous network file servers can directly communicate to tape devices for backup and restore operations. NDMP addresses the problems caused by the integrations of different backup software or DMA, file servers, and tape devices. 

The NDMP architecture is a client/server model with the following characteristics:

• The NDMP host is a file server that is being protected with an NDMP backup solution. The NDMP server is a virtual state machine on the NDMP host that is controlled using NDMP.
• The backup software is considered as a client to the NDMP server.

OneFS supports the following two types of NDMP backups:

• NDMP two-way backup
• NDMP three-way backup

In both the backup models, OneFS takes a snapshot of the backup directory to ensure consistency of data and the backup operates on the snapshot instead of the source directory. Also, this design allows users to continue normal read/write activities. OneFS makes entries in the file history that is transferred from the PowerScale cluster to the backup server during the backup.