Hello, I find a solution to solve my problem. I just add the following instruction into /etc/sysconfig/squid ulimit -SHn 4096 Reboot my server and now : File descriptor usage for squid: Maximum number of file descriptors: 4096 But I always not understand why I have to add this, because I already increased FD on another Squid without that. Note : Squid run under user squid (chroot) -- View this message in context: http://squid-web-proxy-cache.1019090.n4.nabble.com/can-t-increase-Filedescriptor-tp2540496p2543775.html Sent from the Squid - Users mailing list archive at Nabble.com.