If anyone is interested, I've tested bandwidth performance of all of these CDNs using a CDN speedtest here: http://cloudharmony.com/speedtest
I pay users on mechanical turk to run the speedtest and get about 1000 tests run each month from around the world. The speedtest does a single large file test and another test consisting of lots of small files downloaded concurrently like a browser would download a webpage. The results show that the Anycast CDNs (MaxCDN, CacheFly and Cotendo) generally perform better for the multiple smaller files (i.e. CSS, JS, images) due to usually lower latency, while large files generally download faster on the larger (as in more PoPs) DNS-based CDNs like Edgecast and CloudFront. Overall, the top performers based on this testing are Edgecast and CacheFly. CloudFront does well in Apac, but is only about average in the US. GoGrid or Speedyrails resells Edgecast at very reasonable pay-per-use rates.
If you'd like to see the full results of these CDN tests (about 4 months worth of testing so far), I have created a report that shows performance of each CDN globally and broken down into 32 different regions (i.e. US West, EU West, APAC, etc.). I'm happy to share the results, email me if you would like access: jason [at] cloudharmony.com
I'm in the process of doing that... however, for now access requires a user and password which could change over time so I'd prefer not to post it here publicly. If you email I'll provide the access, no strings attached. I'm looking to get some feedback from the report as well.
I recently (2 months ago) started using Cloudfront (on Mugasha.com) for all our static assets. Images, CSS and JS so far, going to move to audio and video assets to Cloudfront spill over soon.
Setup is pretty straight forward, it took a few days to get it right. The main problem with Cloudfront and S3 is that it does not GZIP the files for you on fly based on headers (if browser accepts gzip).
So here is the process I have setup for a rails app.
0. Store all the static assets paths in a config file. LIke this http://grab.by/51Zh. Then I modify the CSS and JS helpers with something like <%= include_stylesheets :common, :media => 'all' %>
1. Make changes to code (js/css/images)
2. Create a folder on s3 with a unique name based on the commit and time stamp. Store that folder name in some config file.
3. Run a script, that uploads all the images to cloud front. Then does a replace in all the CSS and JS file for image urls that are cloudfront based (asset1-5.mugasha.com for background images etc) Then combine, minify and compress/gzip css and js files. Upload files.
4. Commit and deploy.
Each time I run the script and deploy, the asset urls are automatically generated.
I am not sure if this is useful info, but I wanted to share anyway.
This is almost exactly the same process I use as well for RateMyStudentRental and LeadNuke, with a few exceptions.
-Instead of Jammit, I do this with a plugin + manually written Capistrano deploy script.
-Instead of serving CSS and JS (only 2 files since they're combined and cached) from CloudFront pre-zipped, I serve them from my own server, so I can detect the Accepts-encoding header in the incoming request and serve the appropriate file (so as not to leave out the rare request that does not accept gzip encoding).
-Instead of creating a new s3 bucket every deploy and having to recopy the entire contents of the assets folder, I simply sync the existing folders, and let Rails take care of the file caches by updating the appended modified-date in the filenames themselves.
My company was acquired and forced to switch to Akamai. The speed is good, and service is decent. However, the interface is RIDICULOUSLY confusing and they tried to bill us for a ton of different features which our old CDN provided at no cost because akamai had to spend 'hours' coding to enable them on our account.
We currently store about 3gb with Akamai's NetStorage, push roughly 80TB/month in video bandwidth which is about 5 million video views.
We were much happier with our former CDN - BitGravity. They streamed video like no other and had everything ready to go a few minutes after we signed up with them. We also had a stellar support guy named Marco on our account who took care of issues within the hour when we emailed.
Also have a bit of experience with CDNetworks (formerly Panther Express) who were great until they got acquired. Now they have lots of downtime and a very very very annoying sales staff constantly trying to upsell.
I've been using CloudFront for a while but now I'm evaluating Microsoft's Azure CDN. It seems to be a good service so I'm not sure why they're not promoting it on their website.
You have to use Azure Storage, which isn't that much of a problem because the whole service is very similar to Amazon's offering - I was just able to modify existing S3 code. The pricing is also about the same, but what Azure CDN has over CloudFront is a greater number of edge locations, most notably in Australia and South America. I'm really happy with their Asia/Australia performance.
Interestingly, the Azure CDN servers claim to run "EdgePrism", like LimeLight, although they seem to be hosted by Microsoft themselves.
Why isn't Bitgravity in this mix? We use them and love them - and they also power Vimeo, CollegeHumor, and other huge sites. We have used them for images and video content and could not be happier.
Thanks for sharing your setup regarding asset packaging for your rails app (very helpful).
I understand the relationship between CloudFront and S3 and should have been more clear with what I was asking: what is the quantitative difference you've seen in using CloudFront for asset delivery (js+css) versus just using S3? Your pages loading 100ms faster, but at a cost of X dollars more per gigabyte? Certain regions not being able to hit S3?
This sort of bleeds into the "when should I use a CDN?" question. There are lots of recommendations for people using Rackspace Cloud Servers, Slicehost, Linode etc. here on HN. With those hosting providers, I think most people would start off hosting on their local VPS and then at some point say: "I've got to get some of this on a CDN". What was the trigger for your app?
I'm using Edgecast via PAYG at Speedyrails. Means you don't need to pay the ~$350 odd setup fee etc. Very happy with speeds & latency especially here to Australia.
MaxCDN is a really good value and the cheapest for an anycast cdn. vps.net resells akamai for $100/TB ($0.10/GB) which is also a great deal although you don't get netstorage with that (origin pull only). Simplecdn is not a great cdn, we've actually experienced outages on their service and performance generally sucks. cloudfront is good and getting better as they add more pops. If I were to pick a cdn I'd go with edgecast (gogrid or speedyrails resells), cachefly, internap (softlayer resells), cottendo.
> A content delivery network or content distribution network (CDN) is a system of computers containing copies of data, placed at various points in a network so as to maximize bandwidth for access to the data from clients throughout the network.
Doesn't apply to GAE, which just runs from 1 or 2 data centers somewhere.
I pay users on mechanical turk to run the speedtest and get about 1000 tests run each month from around the world. The speedtest does a single large file test and another test consisting of lots of small files downloaded concurrently like a browser would download a webpage. The results show that the Anycast CDNs (MaxCDN, CacheFly and Cotendo) generally perform better for the multiple smaller files (i.e. CSS, JS, images) due to usually lower latency, while large files generally download faster on the larger (as in more PoPs) DNS-based CDNs like Edgecast and CloudFront. Overall, the top performers based on this testing are Edgecast and CacheFly. CloudFront does well in Apac, but is only about average in the US. GoGrid or Speedyrails resells Edgecast at very reasonable pay-per-use rates.