retrieve a db2 backup file

as you don't provide that much information of versions or whatever involved, one can only point to generic approach.

what admin guide are you referring to? the NW admin guide or rather the NW NMDA module admin guide, as that states extensively the various options for DB2 backup and recovery?

https://www.dell.com/support/manuals/en-us/networker-module-for-databases-and-applications/nw_p_nmda_admin_guide_19.8/performing-data-restore-and-recovery-in-db2?guid=guid-98e89eba-749f-4291-ac52-ac62e75fe9a2&lang=en-us

Also I don't quit understand how you picture performing a cross system recovery as that still requires the target system to run a Networker client and have the NW NMDA module installed and configured and have access to the backup infra?

https://www.dell.com/support/manuals/en-us/networker-module-for-databases-and-applications/nw_p_nmda_admin_guide_19.8/performing-db2-data-restores-to-a-different-host?guid=guid-68fd1621-c776-464f-9f16-d9abc482539f&lang=en-us

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1. Create a NetWorker Client resource for the target host.
2. Complete the following attribute and parameter settings for the restore:
   • In the Remote Access attribute in the Client resource of the server A host, specify the username and fully qualified hostname for the remote host that has the DB2 database B. Use the following format for the Remote Access attribute value:

     user=remote_username,host=remote_hostname

   • Set the NSR_CLIENT parameter to the source client hostname for the server A host.
   • Set the NSR_SERVER parameter to the hostname of the NetWorker server that is used for the backup.
3. Complete the restore according to one of the following procedures:
   • Performing DB2 data restores to the same instance
   • Performing DB2 data restores to a different instance
4. On the target host, if the restored database is in the restore pending state, apply the transaction logs according to Performing DB2 recovery with the db2 rollforward command.
5. Complete the following changes for the DB2 database B on the target host:
   • Update the NSR_CLIENT parameter with the target client source hostname.
   • Update the NSR_SERVER parameter if the target database B uses a different NetWorker server.
   • Update the DB2 database B configuration LOGARCHOPT1 and VENDOROPT parameters with the appropriate configuration file pathnames.

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