You need to finish the installation of the Redis Server, as we described in the Downloading and installing Redis recipe in this chapter.

The steps for starting and shutting down a Redis Server are as follows:

$ bin/redis-server

Your server should now start up as shown in the following screenshot:

$ bin/redis-server conf/redis.conf

$ /etc/init.d/redis-server start 

$ vim conf/redis.conf
daemonize yes 
$ bin/redis-server conf/redis.conf

The message Configuration loaded shown in the following screenshot indicates the configuration has already taken place:

$ kill `pidof redis-server` 

$ cd /redis 
$ bin/redis-cli shutdown 

$ /etc/init.d/redis-server stop 

The term instance in Redis represents a redis-server process. Multiple instances of Redis can run on the same host, as long as they use different configurations, such as different binding ports, data persistence paths, log paths, and so on.

Starting and stopping the Redis instance are basic operations. There is not much to note when starting Redis, but for a data service, stopping a Redis service deserves more attention, because as a data store service, it is of great importance for you to learn how to stop the Redis Server gracefully in order to maintain data integrity.

The reason why using the shutdown command to stop Redis is highly recommended is that if you care about data integrity and have already set persistence for Redis to save your data in memory to disk (the persistence of Redis will be discussed in Chapter 6, Persistence), issuing the shutdown command not only terminates the process, but also takes a series of other actions.

First, the redis-server will stop all the clients, and then one persistence action will be performed if the persistence has been enabled. Afterwards, it will clean the .pid file and socket file if there are any, and finally quit the process. By adopting this strategy, Redis does its best to prevent any data loss. Conversely, if the kill command is used rudely, to terminate the redis-server process, data may get lost because it has not been persisted before the server is shut down.

It should be noted that using kill or other process management tools to send a SIGTERM signal (15 signal) to the Redis process is basically equivalent to the shutdown command for gracefully stopping the redis-server.

Configuration parameters can be added to the command redis-server while starting, which is quite useful when deploying multiple instances on a single host. We can have a single configuration file of common configuration parameters used by multiple instances on the same host. Meanwhile, the unique configuration parameters of each instance can be passed in the command line on startup. This way, the cost of maintaining multiple configuration files is eliminated, and instances can be distinguished easily via ps or other system commands.

In addition, you can manage your Redis instance using process management tools such as systemd, supervisord, or Monit, which can also prevent you from messing up when you deploy multiple instances on a single host. All we need to pay attention to are the startup configuration parameters mentioned previously and exit signal handling mechanisms.