NDMP backup jobs that target multiple volumes don't expire based on generations (4043419)

Date: May 08
Product & Version: All
OS Version: All
Module & Version: All
Application version: All

Symptoms:
When running NDMP backups that have more than one volume selected, and when these jobs have a backup life configured based on generations, subsequent runs don't lead to the expiration of previous savesets.

Reason:
Filers have a limitation in that they cannot accept backup requests that contain more than one volume. Consequently, NetVault has to split up those jobs into several subjobs that get created on the fly once the main job is submitted.
Due to this generation on the fly, every time the job runs, new subjobs are created, and because of this subsequent runs of these jobs don't count as a new generations of the previous subjobs, which then stay behind indefinitely.

There are two workarounds:
a) The subjobs will adhere to a backup life based on a date. As such a date is independent of other jobs, all subjobs will expire at the correct time as expected.
b) If jobs are defined directly that only backup one volume each, they can have a backup life based on generations, as they won't have to spawn subjobs themselves.

A feature request (NCG-100) is open to allow for the expiration of subjobs based on generations.