This is crucial tech to understand docker-style containers... I used this to build custom iso images based on an existing iso file. The old method mounted the

This is crucial tech to understand docker-style containers... I used this to build custom iso images based on an existing iso file. The old method mounted the ISO image, rsync'd the entire contents, copied and updated some files, and then created a new image. This took quite a while and (temporarily) wasted a lot of disk space, and was initially sped up by copying the temp ISO to RAM disk, which also presented some challenges, and wasn't as fast as the eventual solution, using aufs on top of the ISO mount to patch the image. Worked like a charm and sped up the ISO building considerably :)