On Wed, 12 Jul 2006, Myron Williams wrote:
I currently have a server with centos 4.3 setup to do email. I use sendmail as the receiving agent and Dovecot as the pop/imap server. Users authenticate off of a openldap server. Under a light load things appear to work fine. However under a moderately heavy load connections are left open in a waiting state. This causes some email to bounce with user unknown, users authentications fails with bad username/password all with valid accounts.
I am trying to figure out what the cause is to fix it but with out success. By restarting ldap and the ldap server I can minimize the problem because the connections get reset. I find nothing when I google on the subject. I don't believe this is a problem with the ldap server because I have a Fedora core machine using it without problems.
Are you running nscd on the client side?
Have you tried bumping the slapd cache on the server side? (The config directive for doing so is specific to the database backend you're using.)