On Tuesday 22 January 2002 08:48 am, Chris McDonough wrote:
Linux Virtual Server works well also as a load balancer. Additionally, Toby Dickenson's recent patch for Zope that allows it to peer with Squid as an ICP server (http://www.zope.org/Members/htrd/icp) is a really interesting thing; it allows for easy failover at the app level as well as rudimentary balancing at the IP level. In comparison, LVS requires that you poll each Zope behind the balancer every so often if you want to detect a failure and react, and unlike any of the fancy $30k load balancers it doesn't look at HTTP response codes to decide if a server returning a "503" error for instance can be taken out of rotation. Zope as an ICP peer has this built-in because it takes the first nonerror response it gets from any Squid peer.
Look at piranha (ha.redhat.com) which is a LVS +some other tools. i'm current ly using piranha to loadbalance zeoclients with nanny(piranha tool) set to check for zeo clients availability by checking the HTTP response (200). if nanny receives a 200, all's ok. else, nanny will take the particular zeo client out of available zeo pool, and add it when it gets the proper response automatically.