Hi, I have three memory only caches set up 7GB of memory each (the machines have 12GB of physical memory each). Throughput is fairly high and this setup works well in reducing the number of requests for smaller files from my backend storage with lower latency that a disk and mem. solution. However, the cache's on of the machines fill up every 2-3 days and Squid's CPU usage subsequently goes up to 100% (These are all dual SMP machines and system load average remains around 0.7). FD's, the number of connections and swap are all fine when the CPU goes up so the culprit is more than likely to be cache replacement. I am using heap GDSF as the policy. The maximum size in memory is set to 96 KB. I am using squid-2.6.STABLE6-4.el5 on Linux 2.6. Is there anything I can do to improve expensive cache replacement apart from stopping and starting Squid every day? J