# Prerequisites

Note the following considerations for NDMP backups:

* If the status of a disk object is *offline*, you cannot browse the disk in the management console or select it for backup.
* The software operating on your NDMP storage system determines the maximum number of NDMP incremental backups of a specific path. For example, NetApp storage systems running supported versions of Data ONTAP support infinite incremental backups. Other appliances support eight true incremental backups of a given path; thereafter, incremental backups behave like DPX differential backups until the next base backup of that path. Consult your NDMP device vendor documentation for specific information on NDMP backup limitations.
* File selection is only supported for NDMP nodes that are running NetApp Clustered Data ONTAP 8.3 or later. For other NDMP node types, you cannot select a descendant resource for exclusion in the source pane of the NDMP backup window.

{% hint style="info" %} <mark style="color:blue;">**Note.**</mark> This capability requires that the NetApp cluster have vServer aware NDMP mode enabled and the following NetApp options also enabled:

```
>set advanced
>vserver services ndmp extensions modify -is-extension-0x2050-enabled true
```

{% endhint %}

* On the source pane, a node expands to the directory/folder level. Underlying files may display but cannot be selected. For NDMP earlier than version 4, the level of expansion is more limited.
* For NDMP appliances that do not support browsing beyond the volume level, such as nodes running NetApp Clustered Data ONTAP 8.2 or earlier, you can right-click on the volume name and use the *Specify New Path* option to manually enter the path to back up.
* If you select multiple subdirectories as source objects, DPX backs up the entire common ancestor.
* The NDMP device vendor may limit or restrict backup and recovery of certain files and folders. These limitations are inherently vendor-specific. Consult your NDMP vendor documentation for access limitations imposed on storage system objects.
* NDMP backup cannot be used to directly protect the master server Catalog. The Catalog restore function does not support restoring data from NDMP archives.
