In this chapter, we will talk about the basic administrative tasks and tools to manage data and its consistency.
There are three features in Cassandra that can make data consistent, and they are as follows:
Hinted handoff
Manual repair
Read repair
Hinted handoff is the process in which if the write is not successful on a node or the node is not able to complete the writes in time, a hint is stored in the coordinator to be replayed at a later point in time when the node is back online.
The downside of this approach is that a node that has been down for a long time comes back online; all the nodes will start to replay hints in order to make the node consistent. These processes can eventually overwhelm the node with hint replay mutations. To avoid this situation, Cassandra replays are throttled by replaying a configured amount of bytes at a time and waiting for the mutations to respond; refer to hinted_handoff_throttle_in_kb
to tune this number.
To...