I have an idea for running a pair of redundant dovecot mail servers that may be odd but it might work. I'm interested in any thoughts on the topic. Would it work to run 'dsync mirror' every minute against either mdbox or sdbox mailbox on a dedicated network connection between two (or potentially three or four) mail servers? I'm trying to avoid using a NAS/SAN or some other dedicated NFS server in a simple environment with a limited number of users. Everything else about the systems could be identical. Both could receive mail using Postfix with dovecot LDA. Thank you. Bryan
On 16.8.2010, at 7.33, Bryan Vyhmeister wrote:> Would it work to run 'dsync mirror' every minute against either mdbox > or sdbox mailbox on a dedicated network connection between two (or > potentially three or four) mail servers? I'm trying to avoid using a > NAS/SAN or some other dedicated NFS server in a simple environment > with a limited number of users. Everything else about the systems > could be identical. Both could receive mail using Postfix with dovecot > LDA. Thank you.Were you thinking about master/slave or multi-master setup? Multi-master might work ok with director, as long as dsyncing is done often enough. If you don't have many users, then maybe dsyncing once a minute is enough. A more optimal version would go something like: - create a dsyncing server process - create a Dovecot plugin (using notify plugin, similar to mail_log) that notifies dsyncing process every time some user's mailbox changes - based on that information, dsyncing process either runs dsync or delays it a bit. like maybe flag changes and expunges would be delayed a bit, but new mails would be immediately synced - run a full dsync for every user once in a while anyway, just in case some notifications were missed - implement a QRESYNC-like syncing for dsync to improve performance and reduce network traffic
I used a setup like this, to sync mail between 3 different datacenters, in a multimaster setup. For this I used unison, running every 28seconds. And it worked well for two years, before I changed to a better approach. Older versions of dovecot didn't like the moves very much (pre 1.0), but when I upgraded it to 1.0.x versions, it seemed to be happy. I discontinued it before 1.1 was out. Quoting Bryan Vyhmeister <dovecot at bsdjournal.net>:> I have an idea for running a pair of redundant dovecot mail servers > that may be odd but it might work. I'm interested in any thoughts on > the topic. > > Would it work to run 'dsync mirror' every minute against either mdbox > or sdbox mailbox on a dedicated network connection between two (or > potentially three or four) mail servers? I'm trying to avoid using a > NAS/SAN or some other dedicated NFS server in a simple environment > with a limited number of users. Everything else about the systems > could be identical. Both could receive mail using Postfix with dovecot > LDA. Thank you. > > Bryan >