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<font face="Tahoma">Hi Mohan,<br>
<br>
here is how we do it. We have also a couple of varnishes sitting
in front of several backend servers. Each backend server responds
to a simple http request on URL <a class="moz-txt-link-freetext" href="http://1.2.3.4/ping">http://1.2.3.4/ping</a> (1.2.3.4 being
the backend server IP). We use this to check the backend server
health in our VCL (in the probe statement). We also use this URL
however to check the health of the varnish servers too. We just
configured our load balancer to access the varnish URL
(<a class="moz-txt-link-freetext" href="http://5.6.7.8/ping">http://5.6.7.8/ping</a>, 5.6.7.8 being the varnish IP address) and
check it's http status code.<br>
<br>
Now, the load balancer will stop sending traffic to the varnish
server either when it is down itself or when all it's backends are
down, which is essentially the same thing, because it means the
varnish cannot serve traffic. We are using restart in the VCL to
make sure that single backend failure will not trigger this. If
one backend goes down, the ping request is served by different
live backend.<br>
<br>
Does it make sense?<br>
<br>
Michal<br>
</font><br>
Dne 15.9.2010 15:25, Mohan Rao napsal(a):
<blockquote
cite="mid:AANLkTikyGPULw8FWaMuQsinzbj0QbDBz8Gfi+WMHLNSv@mail.gmail.com"
type="cite">
<div>Hi,</div>
<div> </div>
<div>Is there a way to probe a varnish server to see if it is
alive ? We have a couple of varnish servers that are load
balanced. We would like the load balancer to stop sending
traffic to a particular varnish server if we are updating that
server. Is there a recommended way to do this ?</div>
<div> </div>
<div>Thanks & Regards,</div>
<div>Mohan</div>
<div> </div>
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<br>
<pre class="moz-signature" cols="72">--
Michal Táborský
chief systems architect
Netretail Holding, B.V.
<a class="moz-txt-link-freetext" href="http://www.nrholding.com">http://www.nrholding.com</a>
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