SSD Vs HDD Speed in Professional and Server Use Cases More often than not, HDDs have been used as storage units in servers, if the data is to be preserved for a longer period of time, particularly when speed of access is unimportant. Some of the biggest factors in choosing hard disk drives over solid-state drives are cost and storage size. The cost per gigabyte of a HDD is lower than an SSD, the difference growing larger as more storage size is required. This is very important in enterprise applications, where drives are bought in bulk and replaced in bulk.