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Just ramping up a new, fairly large & file rich, site with expressionengine and a recent article by metaq touched on cdn and was wondering how one would go about setting it up.

We wouldn't be looking to hook up with amazon and the like, purely 1 or 2 subdomains, ie. mainsite.com resources.mainsite.com library.mainsite.com

I realise all content actually lives on the parent server and is held in domain folders.

Has anyone done this ? Is there significant gains to be had and what are the caveats when using modules like assets, file manager and bootstrap configs.

stuartmcd69
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I realise all content actually lives on the parent server and is held in domain folders.

It sounds to me as though you're not clear on the concept of CDNs. A true CDN is a global network of servers which is optimised for performance serving static files. When files are requested a user will receive a copy from the server closest to them, minimising latency.

A step down from that would be to use a more basic storage network like Amazon S3. When you upload a file to S3 it remains in a specific datacentre, rather than being distributed globally, so performance is worse. Although you won't necessarily see a performance boost from files uploaded to S3 vs your server, you can drastically reduce the load that your server has to deal with. Imagine you have a page with 30 images and 5 CSS & JS files. All of these could be hosted on a service like S3. Instead of your server having to process all of those requests when someone loads a page it only has to worry about the page markup itself. If your site has a large amount of traffic generating a lot of load, this can be the difference between staying up or going down.

Now if you simply serve your static files from a subdomain that's running on the same server as your site, you aren't going to see any benefits. All of the requests are still being routed through the same server - you are only making an aesthetic change.

Dom Stubbs
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  • Great answer. Also Channel Images and some other modules support Amazon S3 natively, so it's a good starting point, even if it's not a true CDN (and CloudFront is an option). – Adrian Macneil Nov 01 '12 at 11:08
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    **Now if you simply serve your static files from a subdomain that's running on the same server as your site, you aren't going to see any benefits. All of the requests are still being routed through the same server - you are only making an aesthetic change.** Not quite true. The reasoning behind serving assets from a separate subdomain is a) so that you can have more concurrent downloads of assets but the main one advocated by Yahoo is b) setting your assets subdomains to be [cookie-free](http://developer.yahoo.com/performance/rules.html#cookie_free). – Tyssen Nov 01 '12 at 21:14
  • Thanks Adrian. @Tyssen "you can have more concurrent downloads of assets" - I can't see why would that be the case. Enlighten me? – Dom Stubbs Nov 01 '12 at 23:18
  • [This article](http://gtmetrix.com/parallelize-downloads-across-hostnames.html) pretty much covers it. – Tyssen Nov 02 '12 at 03:08
  • Interesting, cheers, I hadn't considered it from the browser side of things. Fortunately it sounds as though that's [much less of an issue](http://www.mobify.com/dev/domain-sharding-bad-news-mobile-performance/) with modern browsers though. – Dom Stubbs Nov 02 '12 at 13:36