Hi,
Yes, I am sure it should be possible. NDMP backups just needs to "read" data and therefore even a read-only volume is good enough.
The issue I see in your error is : You are using 'vsadmin-backup' role which is specifically designed for 'Data SVM', and b'cos it is a SVM-DR it probably has it's restrictions I suppose.
Suggestion:
While creating and generating NDMP password for the 'ndmpuser' do not give 'Data SVM' in the -vserver, instead use the 'backup' role, it is created for backup purpose only.
Use the following command:
Create a NDMP backup user with role 'backup':
::> security login create -user-or-group-name ndmpuser -application ssh -authentication-method password -role backup
To confirm it is created:
::> security login show -user-or-group-name ndmpuser
Now, generate NDMP password:
::> vserver services ndmp generate-password -vserver <Admin SVM> -user ndmpuser
Finally, configure/Identify a NDMP data LIF (-preferred-interface-role)
Just go to this section "Configuring SVM-scoped NDMP" in the following link:
https://docs.netapp.com/ontap-9/index.jsp?topic=%2Fcom.netapp.doc.exp-ndmp%2FGUID-476285CF-F6CC-453E-A12A-3080F76BA8AF.html
Summary:
1) Enable SVM-scope
2) Configure a backup user
3) Configure/Identify Data LIF for NDMP backups (Using -preferred-interface-role')
All the information is in the document mentioned above.
Hope this info helps.
Thanks!