To make the data consistent, as administrators, we should repair the nodes at regular intervals. Manual repair or node tool repair is one such way to force Cassandra's nodes to sync the data. Manual repair or anti-entropy repair contains three stages:
Validation compaction
Exchange of Merkle trees and finding the inconsistencies
Streaming
The repair process starts by the user executing the command on a node to repair the given range of data. The node in turn sends a request for validation compaction to all the replicas of the range then waits for the compaction to complete. Validation compaction is the stage in which the node constructs a Merkle tree of the data. Once the Merkle tree is constructed as a result of the validation compaction, the nodes send back the Merkle tress to the coordinating node.
The coordinating node now has all the trees of the entire node for comparison to identify data inconsistencies. Once the inconsistencies are identified, the node sends the ranges to...