Re: [lvs-users] Weird problem with LVS-DR

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Weird problem with LVS-DR
From: Graeme Fowler <graeme@xxxxxxxxxxx>
Date: Wed, 19 Dec 2007 18:42:22 +0000
On Wed, 2007-12-19 at 14:58 +0100, Martijn Grendelman wrote:
> I am a long-time user of LVS, but now I've got a problem that I can't
> seem to solve. Searching the HOWTO and the web hasn't given me anything
> useful, so I turn to the experts now ;-)

[blush] Oh, what, not me? Right ;-)

Anyway: you likely have a pair of "battling" directors. Consider this
(about which I have written before but am damned if I can find it):

Client sends SYN to director1. Director1 sends it on to director2, being
the other realserver - so far this is your scenario.

Director2's LVS catches the packet and sends it back to director1 for
service, but director1 already sent that connection to director2, so
sends the packet back.

With me so far? Good.

What happens now is that second paragraph happens ad nauseum, until your
ethernet between the machines is full up of the same SYN packet,
performance degrades, and the directors fall over under the load

I'll have an archive search shortly and post the workaround!


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