We're ll the process of moving our Drupal 7 online app platform site to a major cloud provider that will include horizontal scaling (multiple nodes for Frontend as well as multiple nodes for MariaDB). We're now considering the optimal solution to scale caching.
We are contemplating substituting standard memcache server with either internal Couchbase memcache server or Redis. The goal is to optimize performance of the site.
We are also contemplating upgrading from php v5.4 to php7.
Please reply if you have experience implementing Couchbase and/or Redis for Drupal 7 sites. We're interested in your experiences with either and your recommendations.
CURRENT SYSTEM CONFIGURATION
* memcached service
* php library (PECL) for memcached
* memcache module by drupal
* nginx (no apache and no apache server libs)
* php v5.4
* current configuration is similar to this setup (except we do not use apache or apache server libs): http://andrewdunkle.com/2012/how-to-install-memcached-for-drupal-7.html
Comments
Quick thoughts
PHP 7 is worth the hassle, do it.
We had issues with high availability & performance with the core database cache and I decided to investigate why the core db cache preformed so bad. I created this module as a result of all of my research - https://www.drupal.org/project/apdqc. This for us simplifies our architecture and I've seen zero performance issues; this is with a 100% logged in site as well (no varnish).
I know from the D6 days that high availability and memcache are tricky, so this gets around that whole issue. See this http://dev.mlsdigital.net/posts/Cloud-Native-Drupal/#remote-data-center-... for some issues that might come up in D7.
If you're worried about the performance of the DB, be sure to run MySQL 5.7; with the right hardware it can do 1.6 million queries per second - http://dimitrik.free.fr/blog/archives/2015/10/mysql-performance-yes-we-c...
As a comparison Redis can do 3 million - https://redislabs.com/benchmarks which isn't that far ahead of MySQL.
Apache server
I was reading a blog recently, which stated that approximately 18.7% of people like to choose apache server as compared to the rest of the options. I was not surprised; rather, I was expecting that the percentage of users will be more than 25.