Hi Ralf, These are good questions. They raise some questions I am still investigating.
On Thu, Jan 17, 2013 at 12:44 AM, Ralf Lang wrote: > > Have you enabled imap caching in imp/config/backends.local.php ? > Does your IMAP server support this setting? No, caching is not currently enabled. Our IMAP backend does not support CONDSTORE or QRESYNC. We may end up enabling it anyway, but probably not. Since we use a pool of load balanced web servers and a user might hit more than one, a local disk cache would end up duplicated and possibly inconsistent, and it is unclear if a shared SQL-based cache would perform significantly better. I wonder about the overhead of repeatedly re-syncing, or worse, simultaneous re-syncs from multiple web servers. Since only one Horde_Cache driver can be selected, a database cache presumably would rule out leveraging eAccelerator or XCache, unless I misunderstand something? I am still exploring this. > Did you consider using up-imapproxy? This is being explored as well. Up-imapproxy is probably not the best choice for our environment because of the need to select between multiple IMAP hosts, so I am also considering NGINX and Perdition. IMP's PERFORMANCE doc seems to imply that it would not work to have an XIMAPPROXY-enabled proxy on each web server potentially accessing the same mailbox on the IMAP host. Conceivably a single imap proxy instance could be used by all the web servers on the network, but that would seem to defeat the purpose. With up-imapproxy, every logged-in user constantly has an open connection to the IMAP server. This would vastly increase the number of simultaneous open connections on our storage engine. This is is currently untested. It may turn out to be fine, but it could end up being a problem. So we need the webmail client to be able to work well without it. NGINX would work well to handle selection of the backend IMAP host, but given its design goals it is unclear if it would be comparable in benefit to up-imapproxy. The host selection can just as easily be done in Horde. In any case, while pursuing these performance considerations is valuable, I still need dynamic mode to be disallowed, at least for now. My solution only partly works actually. I did not consider the case of 'auto'. I think I can work that out, but it's no longer clean and simple. I wonder if a preauth hook is really the best place for it. Thanks Brendan -- imp mailing list Frequently Asked Questions: http://wiki.horde.org/FAQ To unsubscribe, mail: imp-unsubscr...@lists.horde.org
