Linux System Monitoring Tools

reff : http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html

I can see that the best tool to monitor processes , CPU, memeory and disk bottleneck at once is atop …
But the tool itself can cause a lot of trouble in heavily loaded servers and it enables process accounting and has a service running all the time …
To use it efficiently on RHEL , CentOS;
1- install rpmforge repo
2- # yum install atop
3- # killalll atop
4- # chkconfig atop off
5- # rm -rf /tmp/atop.d/ /var/log/atop/
6- then don’t directly run “atop” command , but instead run it as follows;
# ATOPACCT=” atop
This tool has saved me hundreds of hours really! and helped me to diagnose bottlenecks and solve them that couldn’t otherwise be easily detected and would need many different tools