Distributed Systems

The cloud native maturity model

Cloud native maturity model

Consistency Models

(Summary of Strong consistency models)

Concurrent Histories

With several processes, I write to one common storage, that can be spread across multiple nodes.

Light Cones

There is a time slot for the task to write to acknowledge the write. Same for read access.

Linearizability

If a write task was acknowledged, the result is visible for all reading clients.

Sequential Consistency

If something was given to the system in a certain sequence, the visibility will be in the same sequence. Example: posts (A, then B) to a social network are not visible immediately. But if A becomes visible, only after that, B will become visible.

Causal Consistency

Only if operations are dependent from another, they will be given in the correct sequence. For example can read access only be allowed after certain conditions are met.

Serializable Consistency

Is weak because reads and writes can travel to the past and to the future. Is strong because it requires a linearization and certain conditions. The reading history is determined.