Hello, On Sat, Oct 17, 2009 at 11:18:24AM +0200, Angelo Höngens wrote: > Just read this thread, and I thought I would give my humble opinion on this: > > As a hosting provider we use both windows and unix backends, en we use > haproxy to balance requests across sites on a per-site backend (with squid in > front of haproxy). What I would love to see, is dynamic balancing based on > the round-trip time of the health check. > > So when a backend is slower to respond, the weight should go down (slowly), > so the faster servers would get more requests. Now that's a feature I'd love > to see.. And then there would not be anything to configure on the backend (we > don't always have control over the backend application)
Having already seen this on another equipment about 5-6 years ago, I can tell you this does not work at all. The reason is simple : the health checks should always be fast on a server, and their response time almost never tells anything about the server's remaining capacity. Some people even use static files as health checks. What is needed though is to measure real traffic's response time. The difficulty comes from the fact that if you lower the weight too much, there is too little traffic to measure a reduced response time, and it is important to be able to bound the window in which the weight evolves. Regards, Willy
