Building Scaleable Ad Server

We started this journey last year building on top of an open src Ad Server platform(http://www.openx.org).

Here is the short version:
- We were able to handle north of 20m/day traffic with peaks well north of that load
- Yes, we dealt with all kinds of BIG problems you encounter when building scaleable systems
(replication failures, row-level contentions, too many connection to database,
exceeding memory..) and small problems caused by ourselves (binlog filling up, DNS
setup wrong, literally halt-ed a server by accident..)
- At the end, we build a highly scaleable solution with pacing. Then the requirements changed!

More in subsequent postings

Here is a blog post on similar work effort: http://www.mikeonads.com/2010/04/04/the-challenge-of-scaling-an-adserver/