Rachis - RavenDB's Raft Implementation

  • Rachis is the RavenDB's Raft implementation.

  • Definition of Rachis: Spinal column, also the distal part of the shaft of a feather that bears the web.

What is Raft ?

  • Raft is a simple and easy-to-understand distributed consensus protocol.

  • It allows you to execute an ordered set of operations across your entire cluster.
    This means that you can apply a set of operations on a state machine, and have the same final state machine in all the cluster's nodes.
    So any series of events (called a Raft Commands) will be executed in the same order on each node.

  • The Leader Node accepts all the Raft Commands requests for the cluster and handles committing them cluster-wide.
    These Raft Commands are done only if the majority of the nodes in the cluster agreed to it !

Learn More about Raft

What is Rachis ?

Rachis is RavenDB's Raft implementation with the following added features:

  • Support for in memory and persistent large multi-tasks state machines.
  • Reliably committing updates to a distributed set of state machines.
  • Support for voting & non-voting cluster members, see Cluster Toplogy.
  • Dynamic topology, nodes can be added and removed from the cluster on the fly.
  • Managing situations such as handling a Leader timeout and forcing a leader to step down.
  • ACID local log using the Voron Storage Engine.