SSD drives provide the fastest read/write speeds available but are limited in size. Some customers are looking for more storage at a cheaper cost per GB and SATA drives fulfill that need for those who require it.
When ordering the Cloud Plan of your choice you must, at that time, make the decision of whether you want a SATA drive or an SSD for the Storage Device. Once this is chosen it is not able to be changed. The exception to this are our Flex Cloud plans, which are just billed for what they use, not what is ordered.