Oh this is amazing. Read about it today from http://devcentral.f5.com/weblogs/macvittie/archive/2008/08/12/3529.aspx.
Nicely Explained indeed.
Layer 7 load balancing implies that i can absolutely have customised servers with modified kernels and network configuration which are best at spitting out the data that they are supposed to like Static components (css/js/images/static html) or ASP/PHP(Web handlers/severs) or large blobs (Videos for instance) . All these will definitely have varied filesystem network needs, and Layer 7 load balancing allows to group these types and provide them effectively.
