Nearly got caught out with this in the instructions as my current VPS has SSD storage. Optimally, for KVM/Xen/VMWare or dedicated you should configure your server with at least 1GB to 2GB swap space if possible. Fortunately I found this on another hosting site "We do not recommend enabling swap on DigitalOcean or any other provider that utilizes SSD storage." How To Add Swap on CentOS 7 | DigitalOcean