On Mon, Mar 20, 2017 at 8:45 PM, Jason Price <[email protected]> wrote:
> Andrei: > > Why do you care that the cache is synchronized between each remote DC? > 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 - https://www.varnish-software.com/plus/varnish-high-availability/ > > 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. > > 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. > > 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. > On Sat, Mar 18, 2017 at 4:28 AM, Andrei <[email protected]> wrote: > >> (dubbing this over from the mod_auth thread for relevance due to my >> mistake earlier) >> >> 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. >> >> On Fri, Mar 17, 2017 at 8:47 AM, Rodney Bizzell <[email protected]> >> wrote: >> >>> Thanks! >>> >>> >>> >>> *From:* Guillaume Quintard [mailto:[email protected]] >>> *Sent:* Friday, March 17, 2017 9:34 AM >>> *To:* Rodney Bizzell <[email protected]> >>> *Cc:* [email protected] >>> *Subject:* Re: load-balancing >>> >>> >>> >>> The docs have this: http://varnish-cache.org/docs/5.0/reference/vcl.html >>> (you are interested in bereq.backend and req.backend_hint) and >>> http://varnish-cache.org/docs/5.0/reference/vmod_directors.g >>> enerated.html >>> >>> >>> >>> And there is a couple of articles about it: >>> >>> https://info.varnish-software.com/blog/backends-load-balancing >>> >>> https://info.varnish-software.com/blog/backends-load-balancing-part-2 >>> >>> >>> -- >>> >>> Guillaume Quintard >>> >>> >>> >>> On Fri, Mar 17, 2017 at 1:48 PM, Rodney Bizzell <[email protected]> >>> wrote: >>> >>> Hello, >>> >>> In the documentation is there a section on setting-up load-balancing >>> between two varnish servers. >>> >>> >>> >>> This email (including any attachments) may contain confidential >>> information intended solely for acknowledged recipients. If you think you >>> have received this information in error, please reply to the sender and >>> delete all copies from your system. Please note that unauthorized use, >>> disclosure, or further distribution of this information is prohibited by >>> the sender. Note also that we may monitor email directed to or originating >>> from our network. Thank you for your consideration and assistance. | >>> >>> >>> _______________________________________________ >>> varnish-misc mailing list >>> [email protected] >>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc >>> >>> >>> >>> _______________________________________________ >>> varnish-misc mailing list >>> [email protected] >>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc >>> >> >> >> _______________________________________________ >> varnish-misc mailing list >> [email protected] >> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc >> > >
_______________________________________________ varnish-misc mailing list [email protected] https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
