Well if you could diagram or walk-through your specific setup and configs I
can certainly help you (I've deployed probably a couple hundred or so
various load balanced applications using both hardware and software LB
approaches, and with approaches with proxies like varnish too)
The *only* machine directly receiving traffic for a VIP should be the
hardware load balancer itself. It will then decide which (real) machine
(in your case apparently running varnish on top of ?) to send the traffic
on to. If the real machines are answering for the VIP because they're all
sharing a VLAN/LAN then you're going to get failures randomly.
Generally the VIP is configured on a loopback device as a /32 (or /128 in
IPv6) -- return traffic can either be DR or via the LB itself. in the
latter you might be doing NAT in which case the real machines won't have
the VIP configured at all. In a DR situation the real machines have to
have the VIP because they'll send all traffic back to their (default)
router, not the load balancer.
--On Thursday, September 23, 2010 4:23 PM -0700 "Copper, Candace L"
<[email protected]> wrote:
Michael, had the ARP disabled on the VIP and then the site wouldn't load
at all with the VIP and still saw the Unable to connect errors. We
re-enabled ARP and then our site still wouldn't load, and we couldn't
kill any httpd processes and had to reboot.
Just weird stuff happened with that.
Candace Copper
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Michael
Loftis Sent: Thursday, September 23, 2010 10:57 AM
To: '[email protected]'
Subject: Re: Varnish w/hardware loadbalancing woes
Sounds more like a load balancer setup problem than a varnish issue.
Under Linux atleast with DR setups you must disable ARP for the VIP,
unless you're using a tunnel setup or a setup where your VIPs are
completely separate VLAN/LAN.
It sounds like this is what's happening, that the real servers are
receiving the traffic sometimes and the load balancer at others because
of the ARP issue.
--On Thursday, September 23, 2010 9:21 AM -0700 "Copper, Candace L"
<[email protected]> wrote:
I've looked all over for information on how to configure varnish to use
a VIP and have not been able to find much – so I'm hoping someone
here can assist.
Our setup goes like this: Hardware Loadbalancer (sticky sessions enabled)
with one VIP(perf-drupal.domain.com) directs to three Apache identical
webservers (each running Varnish – (perf-drupal1.domain.com,
perf-drupal2.domain.com & perf-drupal3.domain.com)). With the VCL that we
currently have, it works like a charm on each individual server, but when
we try to use the VIP we get errors (50% of the time) when trying to
access the site, stating that it is not available.
I've tried:
backend newsite {
.host = "localhost";
.port = "8080";
}
set req.http.host = "perf-drupal.domain.com";
set req.backend = newsite;
and using the default backend:
backend default {
.host = "127.0.0.1";
.port = "8080";
}
I've read about the DNS Director, but that's not available in the
version I have installed - 2.1.3. But since we are only running one site,
I don't know if it will help. I don't have access to any additional
hardware, so I cannot split out Varnish from the Apache web server.
Any assistance would be greatly appreciated! J
Candace Copper
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