Wanted in inject another discussion heady item into this thread and see if the idea is confirmed in other folks current architecture. Sorry in advance for being verbose.
Often web servers (my experience) are smaller servers, less RAM and fewer CPUs than the app servers and databases. A typical webserver might be a 2GB or 4GB machine with a dual CPU. But, the disk storage on any given webserver will far exceed the RAM in the machine. This means disk IO even when attempting to cache as much as possible in a webserver due to the limited RAM. In this "normal" web server size model, simply plugging a bigger RAM Varnish in upstream means less disk IO, faster web servers, less memory consumption managing threads, etc. This is well proven basic Varnish adopter model. Here's a concept that is not specific to the type of data being stored in Varnish: With some additional hashing in the mix, you could limit your large Varnish cache server to the very high repetitively accessed items and use the hash to go to the backend webservers where ideally you hit a smaller Varnish instance with the item cached on the 2-4GB webserver downriver and have it talk to the webserver directly on localhost if it didn't have the data. Anyone doing anything remotely like this? Lots of big RAM installations for Varnish. I like the Google or mini Google model of many smaller machines distributing the load. Seem feasible? 2-4GB machines are very affordable compared to the 16GB and above machines. Certainly more collective horsepower with the individual smaller servers - perhaps a better performance-per-watt also (another one of my interests). Thanks again everyone. I enjoy hearing about all the creative ways folks are using Varnish in their very different environments. The more scenarios for Varnish, the more adoption and ideally the more resources and expertise that become available for future development. There is some sort of pruning of the cache that is beyond me at the moment to keep Varnish from being overpopulated with non used items and similarly from wasting RAM on the webservers for such. Simple concept and probably very typical. Oh yeah, plus it scales horizontally on lower cost dummy server nodes. _______________________________________________ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
