Date: Mon, 15 Dec 2003 12:33:17 -0800 From: Tim Kientzle <kientzle@acm.org> Cc: freebsd-hackers@freebsd.org Subject: Re: general load balancing issues Message-ID: <3FDE1A8D.600@acm.org> In-Reply-To: <Pine.NEB.3.96L.1031215123851.92111C-100000@fledge.watson.org> References: <Pine.NEB.3.96L.1031215123851.92111C-100000@fledge.watson.org>
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On Mon, 15 Dec 2003, Matthew Seaman wrote: >On Mon, Dec 15, 2003 at 12:46:52PM +0100, Bogdan TARU wrote: > >> I am wondering, though, if I will be able ... to load-balance the domains >> involving sessions: will the sessions be lost when connsecutive hits >> go to different webservers, or not? It depends on where you store the session info, of course. I'm not as familiar with PHP, but I know that Java servlets/JSP default to storing all session info in RAM, which does glue each session to a particular server. Check the load-balancer you're using and see if handles "session persistence." In a nutshell, this gaurantees that successive requests from the same user always go to the same server. This approach has its drawbacks, but it works pretty well in practice. >The canonical answer to this is to store the session data in the >back-end database, so that it's accessible to all of your servers. This depends a lot on the level of traffic you're trying to support. For <100 dynamic pages/second, this is pretty straightforward; I've prototyped systems that could top 10,000 dynamic pages per second using a shared session server, but very few people need that kind of performance. Tim Kientzle
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