The storage component is changing, becoming either dramatically faster with Solid State Disk (SSD) technology or fundamentally more cost effective thanks to capacity-efficient disk archiving or overhead-efficient cloud storage. A four-tier storage strategy will allow storage managers to develop a storage environment that is both cost efficient and meets increasing performance demands. The rapid growth of unstructured data (data not in a database) in most organizations in requiring longer and more managed retention. Database applications as well as applications with incredibly high user counts thanks to web 2.0 are causing performance problems.”]
Source: https://www.darkreading.com/database-security/four-tiers-for-the-new-decade