Redis Tutorial Part 1 – Introduction

Redis – Remote Dictionary Server Redis (Remote Dictionary Server) is an opensource key-value store. It can be used as a database, cache and message broker. Redis is an in-memory store which means that it primarily relies on main memory/primary memory for data storage in comparison to other database storages like Mysql that relies on disk storage.   Redis is written in C language and it supports cross-platform. In-memory databases like Redis are faster compared to disk storage databases like Mysql. Redis is a key-value store. Which means that data is stored like name=’John’ The value john an be accessed using the key name. Key value is a string. Redis is single-threaded(One operation at a time) fast and scalable. The speed allows redis to be used as cache memory. Install Redis on Linux sudo apt-get update sudo apt-get install redis-server For Redis server redis-server For Redis Command Line Interface redis-cli To get configuration for redis goto redis-cli.type CONFIG type of configuration to get configuration values in redis.conf.   There are two processes in Redis architecture. REDIS-CLIENT – Manages client interaction REDIS-SERVER – Manages data storage in the memory and forms the major part of the Redis architecture. Single Redis instance can manage multiple redis…

Redis Tutorial Part 2 – Redis Sentinel and master/slave usage with Node.js ioredis

Redis Sentinel  System designed to help manage Redis instances. As we discussed earlier, one Redis instance can be master and other instances can be slaves. The slaves can have exact data copies of the master server. The master will have replication ID. The biggest advantage of this architecture is that the slave can act as a master if the master fails. Redis Sentinel is the system that helps to make Redis instances with High Availability (HA) by managing failovers. Redis Sentinel Does the following jobs Monitoring – Checking if your master and slave instances are working as expected. Notification – Notifying something went wrong. May be via an API. Automatic failover – If a master is not working as expected, Sentinel can start a failover process where a slave is promoted to master     The configuration file for sentinel is sentinel.conf  redis-server /path/to/sentinel.conf –sentinel   In the sentinel.conf file, there is a line like sentinel monitor mymaster 127.0.0.1 6379 2 quorum – 2 This line determines which master the sentinel is going to monitor. The number 2 is called quorum. The number determines how many sentinels need to agree that the master is having a Failover so that the slave…

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