> http://wiki.squid-cache.org/Features/CacheHierarchy Not quite the same thing. With cache siblings, you have sharing but also duplication of caches. With parents, you will also have duplication - more than 1 parent can have the same copy cached. But there are workarounds. Cache Hierarchy is NOT "controlled by a single squid." as you said. It is controlled by many Squids. With true SMP, no duplication, no workarounds required, and truly the same instance of Squid. I think - corrections welcome.