Red Hat Knowledgebase

There are 3 basic kernel-tuning parameters available for Red Hat Directory Server. The tuning schemes involves NFS mount settings, number of TCP ports, and number of open files.

NFS mount settings

If the Red Hat Directory Server needs to write to a NFS mounted drive, the following changes in the /etc/sysconfig/autofs file are recommended:

LOCALOPTIONS="rsize=8192,wsize=8192,vers=3,tcp"

NFS tuning parameters:

     rsize=8192,wsize=8192 - nfs connection is faster than with the default buffer size of 4096.  

     vers=3 - Specifies which version of NFS protocol to use.  

     tcp - NFS mount will use TCP protocol rather than UDP.

Number of TCP ports

Having enough available local system ports for Red Hat Directory Server requests are also important. TCP tuning can be done by increasing the number of available system ports in the /etc/sysctl.conf file:

net.ipv4.ip_local_port_range = 1024 65000

Execute the command below for the changes to take effect:

sysctl -p

The modifications above will eventually change the value in the /proc/sys/net/ipv4/ip_local_port_range file.

Number of open files

File tuning is required if the current maximum number of files that can be stored on the Red Hat Directory Server is less than 64000.

cat /proc/sys/fs/file-max

Edit /etc/sysctl.conf file and add the fields listed below to adjust these values:

fs.file-max = 64000

Afterwards, increase the maximum number of open files by adding the following line to the /etc/security/limits.conf file:

*	-	nofile	8192

Then, Pluggable Authentication Modules (PAM) pam_limits.so is needed in the /etc/pam.d/system-auth file:

#%PAM-1.0
# This file is auto-generated.
# User changes will be destroyed the next time authconfig is run.
auth        required      /lib/security/$ISA/pam_env.so
auth        sufficient    /lib/security/$ISA/pam_unix.so likeauth nullok
auth        required      /lib/security/$ISA/pam_deny.so

account     required      /lib/security/$ISA/pam_unix.so

password    required      /lib/security/$ISA/pam_cracklib.so retry=3 type=
password    sufficient    /lib/security/$ISA/pam_unix.so nullok use_authtok md5 shadow
password    required      /lib/security/$ISA/pam_deny.so

session     required      /lib/security/$ISA/pam_limits.so
session     required      /lib/security/$ISA/pam_unix.so

Execute the command below so the changes in /etc/sysctl.conf file will take effect:

sysctl -p

Meanwhile, the users will need to log out and then log back in order for the modifications in the limits.conf file take effect.