All-Flash
Storage systems that employ all-flash architectures use only a single type of media: flash. Because of this they are very fast. But, they are also expensive, making them suitable only for those applications where speed at any cost is the driving motivation.
Enterprise storage systems serve two functions – providing read/write access to the data (where speed is important) and storing data (where speed is less important). At any given time only a portion of a storage system's data (the working set) is being read or written by applications, while the remaining data is cold.
Since all-flash systems use a single type of media, all data – even colder data (data that is inactive) – is kept on flash media. This colder data is either stored on expensive flash – which has a higher write endurance – or on less expensive flash – which requires sufficient reserve (larger amounts) to deal with its lower write endurance. Therefore, even though flash does not offer much benefit for storing cold data, all-flash systems still use it to do so. All-flash systems try to compensate for this by supporting in-line dedupe and compression to reduce the systems' effective cost. But even with in-line dedupe and compression, all-flash systems still cost too much for broad deployment. Think of all-flash systems as the private jets of the storage industry. They might be suitable for some applications, such as flying your CEO to important meetings around the world, but for commuting to work on a daily basis, they don't make economic sense.