increase linux file descriptors

Check Installing CentOS 6.2 on VMware and mounting partitions with noatime posts.

This is very important performance tuning for any web server more information here

#adduser www first
ulimit -n unlimited - www
#check default number of concurrently open file descriptors 
cat /proc/sys/fs/file-max
#set the number to high value depending on server config
echo '1773914' > /proc/sys/fs/file-max
echo 'fs.file-max=1773914' >> /etc/sysctl.conf
/sbin/sysctl -w fs.file-max=1773914

install / compile MYSQL 5 on RHEL / CentOS 4

There not much performance difference between MYSQL 4 and 5 as far as you’re not using mysqli ext for your PHP scripts, but it nice to find rpms ready on which makes the job much easier.