Redis cluster (c) Cluster Cluster

Sentry mode, still only one Master node, when concurrent write request is large, can not be written to ease the pressure, appears to solve this problem in version 3.0 Redis-Cluster

Redis-Cluster Cluster features:

　　1) distributed network service cluster consists of multiple servers Redis

　　2) among a plurality of clusters Master main nodes, each node can read a master writable

　　3 communicate with each other) nodes, between two connected

　　4) Redis no central node cluster

Redis-Cluster in the cluster may be added for each node from the master node, the master node and the master node from the follow characteristic model (add a node can be extended to read from the performance of the system)

Failover mechanism Redis-Cluster Cluster:

　　Failover mechanism and Redis Sentinel Redis-Cluster Cluster essentially the same, except that Redis-Cluster failover cluster is responsible for a cluster of other online master node, it is not necessary to additionally use Redis Sentinel cluster

Redis-Cluster cluster fragmentation strategy:

　　Fragmentation strategy is to address key storage location

　　The entire database cluster into 16,384 slots (solt), all key-value data is stored in one of these solt, and can store a plurality of data slots, the key slot is calculated as: slot_number = crc16 (key)% 16384, which is a 16-bit cyclic redundancy crc16 checksum function.

　　Each active node in the cluster can handle 0-16383 grooves, when 16,384 slot has a node at the handles, the cluster enters the online state (and vice versa in a paralyzed state), and start processing transmitted by the client data request command.

Redis-Cluster Cluster redirect

　　Since Redis no central node cluster, the request will be randomly distributed to any of the master node:

　　The master node will only be responsible for handling its own command slot request, the other slot request command, the master node will be returned to the client a steering error;

　　The client re-initiates the command request from the address and port to correct errors contained in the master node is responsible.