Hi I am struggling with the following error: comm_open: socket failure: (24) Too many open files This happens after squid has been running for many hours. I have a Xeon server with 12 cores, 64Gb Ram and 8 x 1Tb disks. The first two are in a RAID-1, and the balance are managed as aufs caches. The system is running 64-bit Ubuntu 12.04 and squid 3.3.6 compiled from source. I am running transparent proxy from two Cisco 7600 routers using wccp2. The purpose is to proxy international bandwidth ( 3 x 155Mbps links). To handle the load I have 6 workers, each allocated its own physical disk (noatime). I have set "ulimit -Sn 16384" and "ulimit -Hn 16384", by setting /etc/security/limits.conf as follows: # - Increase file descriptor limits for Squid * soft nofile 16384 * hard nofile 16384 The squid is set to run as user "squid". If I login as root, then "su squid", the ulimits are set correctly. For root, however, the ulimits keep reverting to 1024. squidclient mgr:info gives: Maximum number of file descriptors: 98304 Largest file desc currently in use: 18824 Number of file desc currently in use: 1974 Each worker should have 16K file descriptors - hence the 98K total I have seen the Largest file descriptor currently in use get up to 26K after some while. max_filedescriptors is not set in squid.conf In spite of the above settings, I eventually get the "Too many open files" messages in the cache.log, and performance deteriorates badly until the load is reduced. I have now set /etc/security/limits.conf as follows: # - Increase file descriptor limits for Squid * soft nofile 65536 * hard nofile 65536 root soft nofile 65536 root hard nofile 65536 Now both root and squid users have ulimits of 65536, Is there anything else I could be doing to prevent this error? Peter