===== Test SWAP impact =====
==== Methodology ====
I will prepare two virtual servers with the same installation and configuration. Next I will try to compile Nagios with empty memory, we will measure with time command the compilation time. Next I will try to compile Nagios with full memory in different server, to get memory full we will use stress command. We will measure swap in and swap out with several tools.\\
\\ I will mantain both virtual machines on.\\
\\ Both machines will have the next configuration:
  * Centos 7.6
  * 1G RAM, 1G SWAP
  * 11G HDD
  * Linux Kernel 3.10.0-957.27.2
  * gcc 4.8.5-36
  * stress 1.0.4-16
  * Nagios 4.4.5
  * 1 vCPU

Nagios compilation compilation will be:
<code>
time make all
</code>
==== Prepare environment ====
<code>
useradd nagios
groupadd nagcmd
usermod -a -G nagcmd nagios
usermod -a -G nagcmd apache
yum install epel-release httpd php php-cli gcc unzip wget glibc glibc-common gd gd-devel net-snmp
yum install stress
cd /root
wget https://github.com/NagiosEnterprises/nagioscore/releases/download/nagios-4.4.5/nagios-4.4.5.tar.gz
tar -zxvf nagios-4.4.5.tar.gz
</code>
==== References ====
  * https://tecadmin.net/install-nagios-core-service-on-centos-rhel/
  * https://www.cyberciti.biz/faq/stress-test-linux-unix-server-with-stress-ng/