On Tue, Mar 3, 2009 at 6:20 PM, Martin Karbon <[email protected]> wrote: > Malcolm Turnbull wrote: >> >> Martin, >> >> Why would the session be lost? >> The second haproxy instance would recognise the cookies and send to >> the correct server in the application pool. >> > > I was just thinking that some information about which client is > connected to which server has to be stored locally on the load balancer > so just sharing the IP using heartbeat and making the process haproxy > start wouldn't do the trick, but I guess I haven't tried that in > practice ... I'll try the failover tomorrow :)
I haven't played with haproxy cookies, yet, but theoretically session information can be baked into cookies such that the cookies presented by the browser tell the load balancer which backend server was maintaining the connection. (F5 supports this as well). >> >> Unless you mean the actual TCP session? >> I'm pretty sure even F5 doesn't support TCP session fail over, and the >> replication of tcp sessions would swamp the network. >> > > The products I've seen were those F5 had to show and I think that what > they meant, as far as I've understood well, was that the tcp session was > carbon copied and kept alive on the backup load balancer so that no > "information" would be lost. But as I said, not having very much > technical knowledge, that is what I have understood. F5 does have an option to do full TCP session mirroring. Of course this has it's drawbacks. (Lowers the traffic a BigIP can handle). In the open source realm Ultramonkey does support some form of session mirroring called, "Connection Synchronization". See: http://www.ultramonkey.org/3/lvs.html for more details. Please keep in mind UltraMonkey is a Linux only load balancing solution, and unlike haproxy can't run on pretty much every modern *nix platform. >> Or have I got the wrong end of the stick as usual? >> >> > > no I guess you got everything right ... btw thanks for the quick answer >> >> >> >> >> 2009/3/3 Martin Karbon <[email protected]> >> >>> >>> Hi! >>> just wanted to know if anyone knows an opensource solution for a so >>> called transparent failover: what I mean with that is, I installed two >>> machines with haproxy on it which comunicate with each other via heartbeat. >>> If one fails the other one goes from passive to active but all sessions are >>> lost and users have to reconnect. >>> I've seen some costly solutions for load balancing which claim to have >>> some sort of shared memory to allow this kind of failover with which users >>> do not lose connection, so I was just wondering if someone knows a product >>> or has some ideas on how this kind of technology is implementable. >>> Best regards >>> Martin >>> >>> >> >> >> >> -- >> Regards, >> >> Malcolm Turnbull. >> >> Loadbalancer.org Ltd. >> Phone: +44 (0)870 443 8779 >> http://www.loadbalancer.org/ >> ------------------------------------------------------------------------ >> >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com Version: 8.0.237 / Virus Database: >> 270.11.7/1982 - Release Date: 03/03/09 16:09:00 >> >> > > > > -- - Brian Gupta New York City user groups calendar: http://nyc.brandorr.com/
