I am unable to do a three-way NDMP backup using Legato NetWorker. My Mirapoint appliance is connected to the NetWorker data management application (DMA), and the tape server is connected to a second Mirapoint appliance that is also connected to the NetWorker DMA. I can back up the Mirapoint appliance that is directly attached to the tape server, but not the other.
NOTE: Before reading this article, Mirapoint highly recommends reading the latest version of the Mirapoint Backup and Restore Guide.
When performing an NDMP three-way backup or restore, an NDMP Mover service is queried by the DMA for an IP address and port number that can be passed to the NDMP Data service (this is the service that performs the actual backup or restore). The Data service then uses this IP address and port number to connect to the Mover. The IP address that is eventually passed to the Data service must be reachable from that system.
When making use of NDMP protocol versions 2 or 3, the number of IP addresses and port numbers that the Mover service can pass back to the DMA is one. If the system the Mover service is running on has multiple IP addresses configured it needs to choose one to pass back to the DMA. The DMA offers no hints as to what is done with the provided address.
Given the above, it is possible for the Mover service to provide a IP address that is unreachable by the appliance that eventually receives it.
It is also possible that the provided IP address is reachable, but not over the expected route (say a GbE network, instead of a 100Base-TX network). There are three possible solutions:
- Run with only one configured IP address on the system running the Mover service.
- Make sure all IP networks on the system running the Mover service are reachable by the appliance running the Data service.
- Some vendors provide a method to tell the Mover service which IP address to prefer when responding to the request from the DMA. Check the vendor provided documentation.