<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 20, 2017 at 8:45 PM, Jason Price <span dir="ltr"><<a href="mailto:japrice@gmail.com" target="_blank">japrice@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Andrei:<div><br></div><div>Why do you care that the cache is synchronized between each remote DC?</div></div></blockquote><div><br></div><div>Because that's the whole point of having a CDN, with High Availability. There's no reason
not to keep cache consistent across the board, and have low latency
per region regardless of requests from that particular region - aka cache priming. For
example, if the origin server in North America receives a cacheable
request from a client, that data is then instantly made available to
all regions. So when client2 from Europe requests the same page,
they get consistent data without the added 100ms+ latency spike per
origin fetch. This is just good common practice for optimizing large
traffic loads and keeping data consistent - imo. Afaik, Varnish Plus
actually offers something along these lines, for a good reason - <a href="https://www.varnish-software.com/plus/varnish-high-availability/">https://www.varnish-software.com/plus/varnish-high-availability/</a></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><br></div><div>The simple way would be to do your any-cast'd IPs be your front end, and have them all talk to a centralized 'private' varnish which fronts the actual service.</div><div><br></div><div>This would allow the individual servers to have a more relevant to their queries cache, and the centralized version would handle any duplication of requests from making it back to the true backend.</div></div><div class="gmail-HOEnZb"><div class="gmail-h5"><div class="gmail_extra"><br></div></div></div></blockquote><div><br></div><div>The anycast IPs are "in front" of the Varnish boxes. However, there
is no "centralized" Varnish to handle the requests as that wouldn't
be optimal for a CDN. The closest by comparison would be the origin
server, in terms of a "centralized version". Think of this setup as a
decentralized mesh which shares data among a set group of Varnish
servers for High Availability and low latency regardless of region.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="gmail-HOEnZb"><div class="gmail-h5"><div class="gmail_extra"><div class="gmail_quote">On Sat, Mar 18, 2017 at 4:28 AM, Andrei <span dir="ltr"><<a href="mailto:lagged@gmail.com" target="_blank">lagged@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>(dubbing this over from the mod_auth thread for relevance due to my mistake earlier)</div><div><br></div>Out of curiosity, has anyone done a CDN of Varnish servers? I have 4 Varnish servers in different datacenters around the world, and use anycast IPs to direct traffic based on the region. I managed to do cache replication using a "fanout" method for new cache hits to be replicated through an intermediary server to the related group of Varnish servers, but was wondering if anyone had a better method of load balancing with cache replication.<br></div><div class="gmail-m_-5714170512109182755HOEnZb"><div class="gmail-m_-5714170512109182755h5"><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Mar 17, 2017 at 8:47 AM, Rodney Bizzell <span dir="ltr"><<a href="mailto:rbizzell@measinc.com" target="_blank">rbizzell@measinc.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div lang="EN-US">
<div class="gmail-m_-5714170512109182755m_1174397131040218617m_-7119767658955909167WordSection1">
<p class="MsoNormal"><span style="font-size:11pt;font-family:calibri,sans-serif;color:rgb(31,73,125)">Thanks!<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span style="font-size:11pt;font-family:calibri,sans-serif">From:</span></b><span style="font-size:11pt;font-family:calibri,sans-serif"> Guillaume Quintard [mailto:<a href="mailto:guillaume@varnish-software.com" target="_blank">guillaume@varnish-soft<wbr>ware.com</a>]
<br>
<b>Sent:</b> Friday, March 17, 2017 9:34 AM<br>
<b>To:</b> Rodney Bizzell <<a href="mailto:rbizzell@measinc.com" target="_blank">rbizzell@measinc.com</a>><br>
<b>Cc:</b> <a href="mailto:varnish-misc@varnish-cache.org" target="_blank">varnish-misc@varnish-cache.org</a><br>
<b>Subject:</b> Re: load-balancing<u></u><u></u></span></p><div><div class="gmail-m_-5714170512109182755m_1174397131040218617h5">
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<p class="MsoNormal">The docs have this: <a href="http://varnish-cache.org/docs/5.0/reference/vcl.html" target="_blank">
http://varnish-cache.org/docs/<wbr>5.0/reference/vcl.html</a> (you are interested in bereq.backend and req.backend_hint) and
<a href="http://varnish-cache.org/docs/5.0/reference/vmod_directors.generated.html" target="_blank">
http://varnish-cache.org/docs/<wbr>5.0/reference/vmod_directors.g<wbr>enerated.html</a><u></u><u></u></p>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">And there is a couple of articles about it:<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><a href="https://info.varnish-software.com/blog/backends-load-balancing" target="_blank">https://info.varnish-software.<wbr>com/blog/backends-load-balanci<wbr>ng</a><u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><a href="https://info.varnish-software.com/blog/backends-load-balancing-part-2" target="_blank">https://info.varnish-software.<wbr>com/blog/backends-load-balanci<wbr>ng-part-2</a><u></u><u></u></p>
</div>
</div>
<div>
<p class="MsoNormal"><br clear="all">
<u></u><u></u></p>
<div>
<div>
<div>
<div>
<p class="MsoNormal">-- <u></u><u></u></p>
</div>
<p class="MsoNormal">Guillaume Quintard<u></u><u></u></p>
</div>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<p class="MsoNormal">On Fri, Mar 17, 2017 at 1:48 PM, Rodney Bizzell <<a href="mailto:rbizzell@measinc.com" target="_blank">rbizzell@measinc.com</a>> wrote:<u></u><u></u></p>
<blockquote style="border-top:none;border-right:none;border-bottom:none;border-left:1pt solid rgb(204,204,204);padding:0in 0in 0in 6pt;margin-left:4.8pt;margin-right:0in">
<div>
<div>
<p class="MsoNormal">Hello,
<u></u><u></u></p>
<p class="MsoNormal">In the documentation is there a section on setting-up load-balancing between two varnish servers.<u></u><u></u></p>
</div>
<p class="MsoNormal"><br>
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