CentOS 6 Setup Guide

System

Disabling unused services

To save system resources, one can disable unneeded services. Our base template (minimal CentOS 6) has disabled many of them by default though. One however has been left alive, which can be safely disabled on most machines:

chkconfig netfs off

Do not disable if you use Network File Systems (NFS).

Setting the time zone

The machine should be configured with the time zone of its physical location. This can be done by running the following commands:

tzselect
tzdata-update

It is very important that your server has correctly configured time zone, as many services rely on valid/synchronized date and time and may fail in case of missing/wrong values.

Sysctl performance tweaks

The following kernel parameters are known to be good:

nano /etc/sysctl.conf

# Tweaking TCP for 100mbps+
net.core.rmem_default       = 256960
net.core.rmem_max           = 256960
net.core.wmem_default       = 256960
net.core.wmem_max           = 256960
net.ipv4.tcp_timestamps     = 0
net.ipv4.tcp_sack           = 1
net.ipv4.tcp_window_scaling = 1

Source: http://systembash.com/content/tweaking-tcp-for-fast-100mbps-connections-and-transfers-on-linux/

Make sure to apply the new settings with sysctl -p.

Within OpenVZ containers, you may not be allowed to set these values.