eBay's engineering team writes about its data infrastructure, search performance, web server management tooling, and open-source projects such as Pulsar and REST Commander.
HN commenters link it for technical details such as REST Commander's actor-based concurrency, Cassandra data modeling, seekable gzip, and archived posts by an engineer.
These are some of the top sites' engineering blogs which I collected over a period of time - I removed those which have already been posted:
Google: http://googledevelopers.blogspot.com/ http://google-engtools.blogspot.com/ http://googleresearch.blogspot.com/
YouTube: http://youtube-eng.blogspot.com/
Baidu: http://usa.baidu.com/category/baidutechblog/
Yahoo: http://yahooeng.tumblr.com/ http://yahoodevelopers.tumblr.com/
Wikipedia (closest I could find): https://blog.wikimedia.org/c/technology/
Amazon: https://aws.amazon.com/blogs/aws/
Twitter: https://engineering.twitter.com/
eBay: http://www.ebaytechblog.com/
Microsoft: http://microsoftengineering.com
FourSquare: http://engineering.foursquare.com/
Apple (closest): https://developer.apple.com/
Paypal: https://www.paypal-engineering.com/ https://devblog.paypal.com/
Dropbox: https://blogs.dropbox.com/tech/
Edit: More (collected from this link: http://www.quora.com/What-are-the-top-startup-engineering-blogs):
Yelp: http://engineeringblog.yelp.com/
Quora: http://engineering.quora.com/
Yammer: http://eng.yammer.com/blog/
AirBnB: http://nerds.airbnb.com/
Square: https://corner.squareup.com/
Flickr: http://code.flickr.net/
Soundcloud: https://developers.soundcloud.com/blog/
Cloudera: http://blog.cloudera.com/blog/
Slideshare: http://engineering.slideshare.net/
Heroku: http://engineering.heroku.com/
Pinterest: http://engineering.pinterest.com/
The idea is that there are a number of complicated tradeoffs that must be made when designing a schema. See [0] for an example; note that every rule comes with an immediate caveat. The result is that you have to be an expert to come up with a great design for a particular system. Even then, if your workload is complex, you might miss a non-obvious choice which will outperform your manual selection.
The goal of NoSE is to automate the process by estimating the cost of executing a workload against a wide range of schema designs. We can then select the one which is likely to perform the best. As far as data migration, moving from a relational database is a reasonable use case. Some of the work I'm doing right now is looking at how you can transition between different schemas in a denormalized database. However, our initial use case was to build something that would allow a non-expert user to design a good schema.
[0] http://www.ebaytechblog.com/2012/07/16/cassandra-data-modeling-best-practices-part-1/
in [part I](http://www.ebaytechblog.com/2015/05/01/fast-approximate-logarithms-part-i-the-basics/) the author argues against using [1,2) because it causes large relative error near x=1 (since log x = 0 there). I would disagree (why would you ever care about relative error in a logarithm -- IMHO absolute error makes much more sense... unless for some crazy reason you're dividing by log x near x=1) but that's his argument.
This is kind of the wrong question. You can trivially run openstack ontop of mesos and vice versa.
Mesos is bigger on services, openstack is bigger on virtual machines. They are different solutions for overlapping, but fundamentally different problems.
Here is an example of Ebay running mesos ontop of openstack:
http://www.ebaytechblog.com/2014/04/04/delivering-ebays-ci-solution-with-apache-mesos-part-i/#.U9qEHnVdWEJ
The core of REST Commander is the actor based concurrency control described at http://www.ebaytechblog.com/2014/03/11/rest-commander-scalable-web-server-management-and-monitoring/ We recently open sourced the http://www.parallec.io/ to support more protocols and I suppose it is not hard to add new protocols if needed.
Agreed on usefulness of random access. Here's a couple more links on seekable gzip compression:
http://lh3.github.io/2014/07/05/random-access-to-zlib-compressed-files/
http://www.ebaytechblog.com/2015/10/09/gzinga-seekable-and-splittable-gzip/