On Mon, Apr 12, 2010 at 8:50 PM, Dirk Taggesell <dirk.tagges...@googlemail.com> wrote: > Hank A. Paulson wrote: > >> How varied is your "site" param? are there many variations or just a few >> similar strings? > > There's a large amount of distinctive urls, maybe some are requested > several times, but still al large amount of different site urls. There > is also another GET parameter, which is some key (one customer, one > key) that is largely constant. but as the url hash should be based on > the site param the key shouldn't matter. > > Only thing is that every site url starts with "http://"; and most also > followed by "www". But that doesn't matter with hashing over the > entire url?
I still do not know why five of seven back-ends don't receive any requests once I activate "hash-type consistent". Without consistent hashing the distribution of requests are almost perfectly even among the back-ends. And I tested with lots of different URLs (an url is given as GET parameter and this parameter is used for hashing). Is there definitely a need for manually weighing the individual back-ends with consistent hashing? That would be quite difficult as I now do only have test urls and not the real ones that will be used in production. And once in production I cannot simply activate consistent hashing only to discover that two back-ends are overloaded while the other ones are doing nothing and me frantically trying to manually distributing the requests by adding weigths to individual back-ends. Sounds quite counter-intuitive to me. So as far as I understood consistent hashing prevents a complete redistribution of hashes among the back-ends but will only redistribute requests that would have gone to a now off-line back-end. So that not all the back-ends caches are being completely invalidated. But needing to manually adjust the back-end distribution will cause problems when the general character of urls our customers send us will change, not?
