Jeremy Cole on InnoDB architecture :

Efficiently traversing InnoDB B+Trees with the page directory    2013-01-15 Jeremy Cole
The physical structure of records in InnoDB    2013-01-11 Jeremy Cole
B+Tree index structures in InnoDB    2013-01-10 Jeremy Cole
The physical structure of InnoDB index pages    2013-01-08 Jeremy Cole
Exploring InnoDB page management with innodb_ruby    2013-01-05 Jeremy Cole
The basics of InnoDB space file layout    2013-01-04 Jeremy Cole
Page management in InnoDB space files    2013-01-04 Jeremy Cole
On learning InnoDB: A journey to the core    2013-01-03 Jeremy Cole
A quick introduction to innodb_ruby    2013-01-03 Jeremy Cole

UNDOs ( Rollback Segments ) :

Allow UNDO logs to reside in their own tablespace 2011-07-26 – Oracle Innodb
Thread Spiral of Death  2010-06-10 - MySQL Performance Blog
Reasons for run-away main Innodb Tablespace  2010-06-10 – MySQL Performance Blog
Tables on SSD Redo/Binlog/SYSTEM-tablespace on HDD  2009-05-12 – Yoshinori Matsunobu
Measuring free space in InnoDB’s global tablespace  2012-09-07 – Baron Schwartz (xaprb)
Shrinking InnoDB system tablespace file ibdata1 PoC  2012-12-08 - Shinguz
Better Scalability with Multiple Rollback Segments  2010-04-13 – John Russell