When DAOS-enabled Domino servers call each other for mail sending or replication, they can transfer file references first, and not transfer the file if it’s already stored in the target server's DAOS.
- We have two DAOS-enabled Domino 8.5 servers: "ServerA" and "ServerB".
- There are replicating databases on both servers and mail DBs of users - "A-User*" on ServerA and "B-User*" on ServerB, and all of the DBs use DAOS, as well as server mailbox’s.
- There are NRPC-connections for mail transfer and replications between these servers.
When A-User1 sends memo with the attached file to A-User2, the file is not transferred and not copied anywhere but remains in one copy in DAOS on ServerA. The same is true even if A-User2 includes a copy of the initial memo with a file into the reply letter and sends it back to A-User1.
Let now the same occur between A-User1 and B-User3. In the initial letter the file is transferred from ServerA to the ServerB. But what will be with the reply? I assume, the file in the response letter will be again transferred between servers, in this case from ServerB to the ServerA. But this file is already stored in DAOS on ServerA! Why two servers communicating by its own proprietary protocol (NRPC), cannot agree among themselves about transfer only references, instead of the file?
That’s the idea! Let DAOS-enabled servers calling each other by NRPC to transfer file references first, and not transfer the file if it’s already stored on the target server.
The same is useful for replications, not only for mail transfer, that is, for any ways of "dialogue" among servers with enabled DAOS.
Especially considerable economy of the traffic can be received with cluster replication of numerous users’ mail DBs. Let’s assume that ServerA and ServerB are connected in cluster, and all users have mail db replicas on both servers. Let the same memo with a file is sent to all users. On delivery of this memo each server’s router will keep one copy of a file in each server’s DAOS. But saving the memo in each user’s mail db will cause it’s replication to other server, thus a file will be again transferred on a network. So we will receive N-fold transfer of the same file between two servers on every memo with a file sent to N users.