Chunk is the basic building block of a cluster to provide the created cluster with a good topology for workload balancing. It consists of 2 proxies and 4 Redis nodes evenly distributed in two machines.
Normally, the first half has 1 master and 1 replica and their peers locate in the second half.
After the second half failed, all the Redis nodes in the first half will become masters.
Instead of complex scheduling strategies and techniques,
undermoon employs a simple Redis node allocation algorithm
to achieve workload balancing:
- The masters should be evenly distributed in all machines.
- After failover happens, in each cluster, the flood of failed masters should be evenly distributed in all machines.
The algorithm detail and the proof of algorithm terminal is documented in chunk allocation.