[lvs-users] LVS servers slowly draining traffic causing outages

[Graeme Fowler]

On Thu, 2008-03-06 at 12:51 -0500, LDB wrote:
> What HOWTO????

*The* HOWTO. The one documenting just about all there is to LVS:

http://www.austintek.com/LVS/LVS-HOWTO/

It's been compiled over the years from many mailing list posts, pieces
of documentation and other sundry sources. It's *very* detailed. I
recommend you read at least some of it.

However, I think you have fundamentally misunderstood one of the
principal problems of LVS-DR. Back to first principles:

For LVS-DR to work properly, the VIP must be present on both the
director(s) and the realserver(s). In systems where the director's IP
(the DIP) and the realservers' IPs (the RIPs) are on the same network -
like yours - then the realservers can respond to ARP requests for the
VIP, which results in the issue you see.

Essentially, all the traffic ends up being handled directly by a (or
more than one) realserver and the director doesn't see it.

This means you have to "hide" the loopback interfaces on the
realservers. See:

http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.arp_problem.html

for a much more detailed explanation of the problem, and the myriad ways
to fix it. For a 2.6 kernel, use the arp_ignore/arp_announce sysctls.

I really, really recommend you read the HOWTO. Alternatively, read
Horms' excellent synopses and examples for Ultramonkey, the most
relevant of which is probably:

http://www.ultramonkey.org/3/topologies/hc-ha-lb-eg.html

Graeme