The layered pattern is common in filesystems and operative systems (and virtual machines for that matter). This pattern consists of creating different layers that go from the raw data through to the data seen by a user:

The idea is to separate the complexity of the different layers, each one not having to know how the others do their tasks:

• Handling the data structures and storing them in a fast and secure way
• Manipulating the data structures and adding business logic to them
• Handling user requests and showing the data in a localised format