On Aug 16, 2010, at 6:00 PM, Elliot Murphy wrote: > On Mon, Aug 16, 2010 at 7:47 PM, Michael Hudson > <[email protected]> wrote: >> On Fri, 13 Aug 2010 11:56:47 +0100, Gavin Panella >> <[email protected]> wrote: >>> If what I am seeing is valid, then I can see two - I assume relatively >>> easy - things we can do to help: >>> >>> - Only publish one address for each vhost. >>> > > I believe two addresses are published so that browsers round-robin DNS > support will failover to the second machine in the case of a webapp FE > server failure. Significantly speeding up SSL would be a worthwhile > reason for moving to another scheme, but you would probably want to do > something to replace the failover mechanism that you are removing. I > think a typical solution is to use a virtual IP with some kind of > heartbeat to let the second frontend takeover if the other one dies. > The downside of something like this is that you are no longer running > active-active on the front ends (I think?). >
DNS RR's really only have one good place anymore, and that is cheap multi-site failover. Even then, they suck because when one site goes down, some clients will keep retrying it, slowing their site responsiveness. Newer browsers at least will wait a very short time to try all of the RR's, but this also creates issues as the request may actually be half-complete when the browser decides it is time to switch (to be fair, I've only seen that from ie). Basically, the loss of active-active is probably a tiny little trade off of utilization for a huge payback of predictability. Given that there's only two IP's per node that I looked up, I doubt active-active is even worth it, given that in a 2 node active-active cluster, each node has to be able to handle all of the traffic anyway, otherwise a failure takes the whole service down. _______________________________________________ Mailing list: https://launchpad.net/~launchpad-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~launchpad-dev More help : https://help.launchpad.net/ListHelp
