An engineer from github lays out why he’s an lvs/ldirector guy and the author of ha proxy jumps in with a lot of info about the advantages of an L7 proxy approach.
via Load balancing at Github: Why ldirectord? | Anchor Web Hosting Blog.
Overall I’ve sided with the L7 approach to the tune of several hundred grand over the last few years. The massive bag of tricks you get at the HTTP layer is just too hard to live without once you’ve been there. Of course, its also the coolest rope I ever hanged myself with.
Conversely I’ve used the “DR” approach that LVS supports (was actually an ibm product but worked the same way) and seen it cause issue after issue after issue to the point where I’d never go back unless I had a huge clear architectural need.