To ensure good server performance, the total number of client connections, database files, and log files must not exceed the maximum file descriptor limit on the operating system (ulimit -n). By default, the directory server allows an unlimited number of connections but is restricted by the file descriptor limit on the operating system. Linux systems limit the number of file descriptors that any one process may open to 1024 per process. (This condition is not a problem on Solaris machines, x86, x64, or SPARC).
After the directory server has exceeded the file descriptor limit of 1024 per process, any new process and worker threads will be blocked. For example, if the directory server attempts to open a Oracle® Berkeley JE database file when the operating system has exceeded the file descriptor limit, the directory server will no longer be able to open a connection that can lead to a corrupted database exception. Likewise, if you have a directory server that exceeds the file descriptor limit set by the operating system, the directory server can become unresponsive as the LDAP connection handler consumes all of the CPU's processing in attempting to open a new connection.
To fix this condition, set the maximum file descriptor limit per process on Linux machines.
The hard limit is the maximum server limit that can be set without tuning the kernel parameters in proc file system.
$ ulimit -aH core file size (blocks) unlimited data seg size (kbytes) unlimited file size (blocks) unlimited max locked memory (kbytes) unlimited max memory size (kbytes) unlimited open files 1024 pipe size (512 bytes) 8 stack size (kbytes) unlimited cpu time (seconds) unlimited max user processes 4094 virtual memory (kbytes) unlimited
* soft nofile 1024 * hard nofile 65535
session required /lib/security/pam_limits.so
The system file limit is set in /proc/sys/fs/file-max .
echo 65535 > /proc/sys/fs/file-max
ulimit -n unlimited