Install GuestAdditions into a Virtual Machine to improve Virtual Machine

Install GuestAdditions into a Virtual Machine to improve Virtual Machine's System Performance. The example below is to install GuestAdditions on a Virtual Machine "CentOS_7".
[1]	Attach GuestAdditions' disk to the VM on VirtualBox Host.

[root@dlp ~]#  VBoxManage storageattach CentOS_7 \ --storagectl CentOS_7_SATA \ --port 0 \ --type dvddrive \ --medium /usr/share/virtualbox/VBoxGuestAdditions.iso

[2]	Install GuestAdditions on the VM.

# install some packgaes [root@guest ~]#  yum -y update kernel  [root@guest ~]#  reboot [root@guest ~]#  yum -y install gcc make bzip2 kernel-devel [root@guest ~]#  mount /dev/cdrom /mnt  [root@guest ~]#  cd /mnt  [root@guest mnt]#  ./VBoxLinuxAdditions.run  [root@guest mnt]#  reboot

[3]	After installing GuestAdditions, System Performance is improved.