I have four squid-3.1.6 instances with IDENTICAL config, clustered using ldirector. One of those proxies is using many more FDs: squidclient -p 8080 -l 127.0.0.1 mgr:info | grep 'file descri' Maximum number of file descriptors: 8192 Available number of file descriptors: 3430 Reserved number of file descriptors: 100 The other three: Maximum number of file descriptors: 8192 Available number of file descriptors: 6500 Reserved number of file descriptors: 100 Maximum number of file descriptors: 8192 Available number of file descriptors: 6691 Reserved number of file descriptors: 100 Maximum number of file descriptors: 8192 Available number of file descriptors: 6653 Reserved number of file descriptors: 100 What are the filedescriptors used for? -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 | D-12203 Berlin Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962 ralf.hildebrandt@xxxxxxxxxx | http://www.charite.de