On Wed, 10 Mar 2010, Klemens Kittan wrote:
Mar 1 14:45:15 ldap1 slapd[25320]: warning: /etc/hosts.allow, line 19: cannot open /etc/hosts.allow: Too many open files
cat /proc/sys/fs/file-max: 203609
cat /proc/<slapd pid>/limits: Max open files 4096 4096 files
Sounds like you're mostly on the right track, but I didn't hear mention of compiling with a suitable OPENLDAP_FD_SETSIZE. Are your CPPFLAGS set accordingly?