We are having problems with our Squid servers during traffic peaks. We had problems in the past and we got different error such as "Your cache is running out of filedescriptors", syncookies errors, etc. but nowadays we have optimized that and we are not getting those errors anymore. The problem is that the servers, which many of them are different in resources and in two different datacenters (which are all running squid as a reverse proxy caching contents from several webservers in other datacenters), during big traffic peaks all of them fail to deliver content (html pages, js files and css files gziped and non gziped as well as images) and we do not see any error at all. The more connections/requests, the highest is the percentage of clients that fail to get the content. So we are trying to find out where is the bottleneck. Is Squid unable to deal with more than X connections per second or is there any other bottleneck related to Squid? I think the bottleneck starts when there is around 20,000 connections to each server.
We are currently using Squid on CentOS and the "load balancing" and failover is done with DNS round robin and DNS fail over but we might consider using pfsense+Squid on FreeBSD if can definitely help to avoid this bottlenecks.
Thank you in advance