1 Reply Latest reply on Apr 23, 2010 9:10 AM by michael_schneider

    Webwasher in High Availability Mode

      I can't seem to find a guide on setting up Webwasher in HA mode and the different options that are available to us.  The help file had a little information, but it didn't quite explain all the options thoroughly.  Here are some of my questions:

       

      1. What are the different options we have to do load balancing?  So far, I've found the following:
        • Built HA
        • DNS Round Robin
        • URLhash via proxy.pac (some more info on this one would be nice)
      2. How do we set up HA mode using the built in option?
        • Do we need to set up a crossover cable for the heartbeat interface?
        • How do we go about setting up the virtual IP?  Do we just choose one and both Webwasher's will automatically know to use it?

       

      Thanks all.

        • 1. Re: Webwasher in High Availability Mode
          michael_schneider

          Hello,

           

          right, you have most of the options listed already. For completeness I am adding the external load balancer option:

          • Built-in HA
          • DNS Round Robin
          • URLhash  via proxy.pac (some more info on this one would be nice)
          • external load balancing using load balancer

           

          Hash routing provides:

          1. Scalability:No communication  between proxy caches
          2. Deterministic  fast routing at client and/or proxy
          3. even or heterogeneous load balance control
          4. No  duplicated caching/efficient use of  storage
          5. Robustness for  failure/re-configuration

          The basic idea is  that once hash routing script is downloaded in Web browsers and if  there are N proxies, then

          1. Hash  routing script converts URL string into check  sum (random hash number which is  calculated uniquely from URL string)
          2. calculates hashing function i = Modulo(checksum(URL),N) for each requested  URL.
          3. route client request to i-th  proxy


          (taken from http://www.pacfiles.com/images/SSP.htm)

           

          For the built in one, you don't need a X-cable between the two instances it can communicate over a ususal network. As the HA is using broadcasts it is noteable that the two device must be in the same broadcast domain in order to let broadcasts appear on the single instances.

          The VIP needs to be a free IP in the same subnet of the Webwashers, which can be set in each WW's UI, You obviously need to make sure you configure both with the same.

           

          thanks,

          Michael

           

           

          Message was edited by: Michael Schneider on 4/23/10 9:10:55 AM CDT