Avamar: Avamar NDMP Celerra/VNX subvolume incrementals

There are times when it is necessary to back up a directory below the volume level for Celerra, VNX, and Unity systems.

To configure a sub-volume backup, modify the dataset and enter the path to the directory to be backed up.
The path must be a directory. File backups are not supported.

By default, the backup for any sub-volume backup is a Full - Level 0 backup. The reason is that if there are links from the sub-volume to somewhere outside this sub-volume, only the link is backed up.  

A Full backup backs up the link and the data.

To force an incremental backup for these sub-volumes, use the allowsubvolumeincremental flag.
Only use this after due diligence has been done. NO data pointed to by a link is backed up in this sub-volume.

Below are two ways to set this parameter.

In the Avamar Administrator UI, edit the dataset Dataset Advanced Options.
Set the parameter: [avndmp]allowsubvolumeincremental
Set the value: true

Alternatively, modify or create an avndmp.cmd file under the client folder on the NDMP accelerator node.

For example:
/usr/local/avamar/var/CLIENT_DIR/avndmp.cmd

The file should contain:

--allowsubvolumeincremental

The first method (GUI config) sets the parameter for all clients via the general dataset.
The second method (cmd file) only sets it for that one client.

A full backup will need to be performed the first time as normal.  This should occur automatically.
Subsequent backups will be incremental backups.