Vagrant在CentOS6底下要設定nfs同步本機sharefolder，要在Vagrantfile加上

config.vm.synced_folder "../data", "/vagrant_data", type:"nfs"

還要在VirtualBox要裝Extension，然後vagrant要在裝下面這個plugin才可以

vagrant plugin install vagrant-vbguest

參考：

• https://stackoverflow.com/questions/42074246/vagrant-error-unable-to-mount-virtualbox-shared-folders-guest-additions-vboxs
• https://www.vagrantup.com/docs/synced-folders/nfs.html