You might decide to perform backups within the non-global zones in the following cases.
The non-global zone administrator needs the ability to recover from less serious failures or to restore application or user data specific to a zone.
You use the backup software of a particular application or service running in a zone. It might be difficult to execute the backup software from the global zone because application environments, such as directory path and installed software, would be different between the global zone and the non-global zone.
If the application can perform a snapshot on its own backup schedule in each non-global zone and store those backups in a writable directory exported from the global zone, the global zone administrator can pick up those individual backups as part of the backup strategy from the global zone.