Paul J Stevens wrote: > Some kind of replication of the dbmail_users table across database > servers would still be required, like we do now between ldap and sql. > That would allow *any* of the database backends to function as the > primary backend - in fact, any of the active daemons/tools would be able > to use any of the backends for it's initial database connection, > switching to another if the authenticated user so requires. > > My thought on separating the tables like I had stated is that you could have a circular replication cluster or ndb cluster on the front end that all the daemons could use, that would include the acl and mailboxes tables. Changes to these tables few and far between, making the replication of data in this front-end cluster much faster than that of message insertion and cleanup. The rule set on which backend database to put mailboxes could be per mailbox or per user or mixed. If the rule was per user, the first 10 mailboxes would be created on the server set on the users row setting. If that setting changed, then new mailboxes would go to a different backed. The backend servers could be a simple master-slave or master-master replication setup with only 1 server in that cluster talking to dbmail. I think this approach with a fully replicating front-end cluster and multiple backend clusters could be used to have a huge user base around the world, with users being homed to a backend near their actual location, and using a front-end connection at that same site.
I could have data center locations in Los Angels, New York, London, and India. I have users all around, but primarily closer to one of those areas. The user would use the pop3 or imap that is running at their closest data center. The rule is set such that their backend is one of the backends at that same data center. But I have developers in India and Los Angeles that need to be able to access a public mailbox on a New York backend. The front-ends are replicating over a vpn or private links. The dbmail daemons would also be able to connect to any backend over this private meshed network. I'm in Los Angeles and open the Public mailbox - that mailbox data is pulled from New York to Los Angels to the daemon I'm connected to, then the results are sent on to me the client. Same as if I had done the same connecting to the India site. This should not break any functionality as each mailbox is fully stored on the same backend. I do like the approach of having it per mailbox, as some users have a lot of email in a lot of mailboxes. Of course all of this advanced separation of message storage could be essentially disabled by just putting all the tables on the same database server as in backend #0 - the default. -Jon -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Dbmail-dev mailing list Dbmail-dev@dbmail.org http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail-dev
