1 Reply Latest reply on Jul 6, 2006 7:49 AM by Newsgroup_User

    CF7 Multiserver configuration question

    paulkeogh
      The CFMX 7 install guide states;

      <quote>
      Load balancing and failover You deploy the same application to each server instance and add
      the instances to a cluster. The web server connector optimizes performance and stability by
      automatically balancing load and by switching requests to another server instance when a server
      instance stops running.
      </quote>

      What exactly does "stops running" mean here from the connector perspective ? Is it;

      * HTTP requests fail (and if so what status codes are regarded as permanent failures)
      * TCP connectivity is lost
      * Something else ?

        • 1. Re: CF7 Multiserver configuration question
          Level 7
          paulkeogh wrote:
          > What exactly does "stops running" mean here from the connector perspective ?
          > Is it;
          >
          > * HTTP requests fail (and if so what status codes are regarded as permanent
          > failures)
          > * TCP connectivity is lost
          > * Something else ?

          In my experience with this, if you're talking about the CF level of
          clustering specifically, the failover from one CF instance to another
          occurs when a CF request fails. This doesn't have anything to do with
          HTTP requests so if your web server isn't clustered the CF clustering
          isn't going to help you there.

          We did a lot of analysis on this recently as we built a new
          high-availability environment. The basic question you have to answer is
          when a physical server is considered "down" and should be taken out of
          service. At a high level you have three situations to consider:
          1. Box is up and running and responding to TCP/IP traffic, but IIS is down
          2. Box is up and running, but CF is down
          3. Box is dead

          CF clustering doesn't help you with IIS being down, and of course it
          doesn't help you if the box is down. The absolute best solution overall
          is a hardware load balancer because that can (depending on your load
          balancer) help you at both the box level and the IIS level, and with a
          bit of extra work even with the CF level.

          In our situation we decided that since we have three servers, if any one
          of the three situations above occurs, the box is considered out of
          service and the load balancer fails over to another box. We could
          cluster CF but decided it wasn't worth the effort and additional
          overhead in our situation. Your needs may dictate otherwise of course.

          Hope that helps,
          Matt
          --
          Matt Woodward
          mpwoodward@gmail.com
          Adobe Community Expert - ColdFusion