This is meant to be a series, so the second article (which talks about the Image Store) is found here: <a href="http://blog.scalr.com/post/55282745486/cloud-native-the-image-store" rel="nofollow">http://blog.scalr.com/post/55282745486/cloud-native-the-imag...</a> (Didn't want to spam post!)
I think it was Randy Bias that introduced the idea of pets vs cattle. See his presentation at <a href="http://www.slideshare.net/randybias/architectures-for-open-and-scalable-clouds" rel="nofollow">http://www.slideshare.net/randybias/architectures-for-open-a...</a>