ParElastic http://drupal.org/node/1846896

ParElastic is the only solution that brings the flexibility of cloud architectures to all dimensions of your database.

CDNs, caching (such as with memcached or redis), and read-only MySQL slave servers can scale Drupal for anonymous, read-only traffic. However, these approaches do not help scale Drupal to handle increased dynamic page generation (such as for logged-in users) or heavy loads (such as high comment volume). Also, Drupal 7's support for read-only slave servers is incomplete, with many contrib modules not supporting it at all.

ParElastic is a solution for horizontally scaling MySQL in a way that allows elastically-scalable read and write capacity while maintaining 100% compatibility with existing Drupal core and contrib modules.

With ParElastic you can:

• Improve your Drupal site's response time under heavy load.
• Handle increased data volume as your site gains popularity.
• Dramatically reduce the cost of operating the database servers that power your site.

Flexible Development

• Standard SQL with no compromises (including cross shard operations)
• Standard tools and interfaces
• Use existing MySQL applications unmodified

Flexible Deployment

• Scale your existing database
• Leverage existing investments – use any version of MySQL, any storage engine, any HA, backup or other admin tools
• Deploy to a data center, public or private cloud

Flexible Operations

• Don’t over provision, expand as workload demands
• Add capacity for storage or processing power independently
• Pay only for what you use

Led a Birds of a Feather meetings "How to scale out MySQL in support of Drupal" DrupalCon Munich 2012 and DrupalCon Denver 2012
Acquia webinar October 23 - How to scale MySQL in support of Drupal
http://www.acquia.com/resources/acquia-tv/conference/how-scale-mysql-sup...