Some good points raised on the subject. I thought it might spark a few posts.
Just so people are aware, i've currently setup two remote postfix/dbmail machines Server 1 (postfix + dbmail + mysql) server 2 (postfix + dbmail + mysql) Both in master-master replicating and working Roundrobin equally weighted mx's I'm currently only connecting to imap on server2 but everything else appears to be ok... at the moment. It's only a small testbed setup with about 20users. I guess i'm just experimenting to see if it works well or not. With regards to master-master replication i'm using the staggered auto increments. Kind Regards James Greig - AS33854 - AS45014 Nuco Technologies Ltd [EMAIL PROTECTED] www.nucotechnologies.com Tel. 0870 165 1300 Nuco Technologies Ltd is a company registered in England and Wales with company number 04470751 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gordan Bobic Sent: 12 June 2008 23:54 To: DBMail mailinglist Subject: Re: [Dbmail] replication Paul J Stevens wrote: >>> I've probably asked this before however can someone remind me why mysql >>> master-master (innodb) replication is not recommend with dbmail? >> It's not "recommended" with anything. By the very nature of it, there is >> a potential very nasty race condition inherent in multi-master MySQL >> replication. In practice you'd have to be extremely unlucky to encounter >> it, but since there is no cluster-wide locking available in this setup, >> it is a possibility. FWIW, I use it with multi-master replication. YMMV. > > These conditions will not be very rare at all once you start putting > pressure on it. > > But there is another reason in the imap requirements: UID values must be > strictly ascending within a mailbox. > > Since these UID values are the autoincremented primary key on the > mailboxes table the only way to avoid collisions in the first place is > by stepping them differently on the separate masters, but doing that > will collide with the imap requirement I mentioned. Hmm... I'll have to think about that case and try a few tests. Unless there is a serious race condition encountered (which will only happen if the same user has multiple simultaneous connections to separate servers), I think the staggered auto-increments will still resolve correctly (there will just be holes in the key-space, which I don't think would cause problems). I'm not saying it's a good idea, but I think the scope for a damaging race condition is reasonably limited. Gordan _______________________________________________ DBmail mailing list [email protected] https://mailman.fastxs.nl/mailman/listinfo/dbmail _______________________________________________ DBmail mailing list [email protected] https://mailman.fastxs.nl/mailman/listinfo/dbmail
