A few months ago, we worked with Ziggo in Netherland, to help them transition their legacy environment to ForgeRock I3 Open Platform. Part of the transition, they’ve replaced Sun Directory Server Enterprise Edition (DSEE) with OpenDJ, running in 3 data-centers (and different sites), and over 2.5 Million entries, in a very smooth and well controlled migration process.
They’ve now been running OpenDJ and OpenAM in production for a few months and we’re really happy to be able to share the details of the story with you. Get the Ziggo Case Study (PDF).
You can find more details about OpenDJ on ForgeRock web site.
Ludo Sketches 
The link to the case study is invalid …
Thanks for the report.
It’s a known issue, we’re working on restoring the links and case study.