Ubuntu16.04.1上搭建分布式的Redis集群，并使用C#操作

为什么要集群：

通常为了，提高网站的响应速度，总是把一些经常用到的数据放到内存中，而不是放到数据库中，Redis是一个很好的Cache工具，当然了还有Memcached，这里只讲Redis。在我们的电商系统中，热点数据量往往巨大，比如单点登录、用户浏览商品的信息、用户信息、用户收藏的商品信息、短息提醒数据等等，也都用到了redis，如何使redis可以横向可伸缩扩展，这需要由多台机器协同提供服务，一台挂掉了，另一台马上顶上去，即分布式的redis集群，就对系统的性能非常重要。

Redis集群的几个重要特征：

(1).Redis 集群的分片特征在于将键空间分拆了16384个槽位，每一个节点负责其中一些槽位。

(2).Redis提供一定程度的可用性,可以在某个节点宕机或者不可达的情况下继续处理命令.

(3).Redis 集群中不存在中心（central）节点或者代理（proxy）节点，集群的其中一个主要设计目标是达到线性可扩展性（linear scalability）。

(4).Redis集群要想正常工作，必须要三个主节点，在我搭建的集群环境中，三个主节点都需要有一个从节点，所以一共六个节点，通俗来讲也就是需要开启6个redis服务。

一、安装Redis

关于如何在Linux上安装Redis，可以参考我的这篇博客，里面有详细的安装步骤，注意在搭建Redis的集群环境我使用的Redis版本为4.0.1《Redis的安装以及在项目中使用Redis的一些总结和体会》。

整体结构：

二、进群环境的配置

（1）在这里我就开启三台Ubuntu16.04.1，因为电脑8G的内存不够用，如果你电脑内存大可以开启4台或者更多。在这三台中我都安装好了最新版本的Redis。

（2）集群配置文件的修改

第一台配置文件的修改：首先在usr/redis目录下，把上面安装好的的redis文件放到该目录下面，具体哪些文件可参考下图。

需要的文件有：

然后通过下面的命令把上面的文件复制到usr/redis/目录下面：

首先在usr目录下面创建一个redis和s2目录：sudo mkdir redis; sudo mkdir s2

目录创建好后，到上面图中的目录下面，打开终端，执行：cp redis* /usr/redis/，上面图中的文件就会到usr/redis/目录下面，最后到usr/redis/目录下面，打开终端，执行sudo cp redis* /usr/redis/s2/，这是该目录下面也就会有相同的文件了。

修改redis.conf文件中Cluster的配置，修改如下：

首先由于权限的问题，我们先要切换到root身份：sudo passwd root命令，先修改root的密码，修改之后，再执行su root 接着输入你设置的root密码就可以切换到root身份，如下：

最后在root身份执行下图中的命令就可修改redis.conf文件：

这里只贴出来修改的代码：（红色标注的部分为修改部分）


# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# bind 127.0.0.1  //注释掉

# Protected mode is a layer of security protection, in order to avoid that
# Redis instances left open on the internet are accessed and exploited.
#
# When protected mode is on and if:
#
# 1) The server is not binding explicitly to a set of addresses using the
#    "bind" directive.
# 2) No password is configured.
#
# The server only accepts connections from clients connecting from the
# IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
# sockets.
#
# By default protected mode is enabled. You should disable it only if
# you are sure you want clients from other hosts to connect to Redis
# even if no authentication is configured, nor a specific set of interfaces
# are explicitly listed using the "bind" directive.
protected-mode no   //yes该为no

# Accept connections on the specified port, default is 6379 (IANA #815344).
# If port 0 is specified Redis will not listen on a TCP socket.
port 6379

# TCP listen() backlog.
#
# In high requests-per-second environments you need an high backlog in order
# to avoid slow clients connections issues. Note that the Linux kernel
# will silently truncate it to the value of /proc/sys/net/core/somaxconn so
# make sure to raise both the value of somaxconn and tcp_max_syn_backlog
# in order to get the desired effect.
tcp-backlog 511

# Unix socket.
#
# Specify the path for the Unix socket that will be used to listen for
# incoming connections. There is no default, so Redis will not listen
# on a unix socket when not specified.
#
# unixsocket /tmp/redis.sock
# unixsocketperm 700

# Close the connection after a client is idle for N seconds (0 to disable)
timeout 0

# TCP keepalive.
#
# If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
# of communication. This is useful for two reasons:
#
# 1) Detect dead peers.
# 2) Take the connection alive from the point of view of network
#    equipment in the middle.
#
# On Linux, the specified value (in seconds) is the period used to send ACKs.
# Note that to close the connection the double of the time is needed.
# On other kernels the period depends on the kernel configuration.
#
# A reasonable value for this option is 300 seconds, which is the new
# Redis default starting with Redis 3.2.1.
tcp-keepalive 300
################################ REDIS CLUSTER  ###############################
#
# ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however
# in order to mark it as "mature" we need to wait for a non trivial percentage
# of users to deploy it in production.
# ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#
# Normal Redis instances can't be part of a Redis Cluster; only nodes that are
# started as cluster nodes can. In order to start a Redis instance as a
# cluster node enable the cluster support uncommenting the following:
#
cluster-enabled yes

# Every cluster node has a cluster configuration file. This file is not
# intended to be edited by hand. It is created and updated by Redis nodes.
# Every Redis Cluster node requires a different cluster configuration file.
# Make sure that instances running in the same system do not have
# overlapping cluster configuration file names.
#
cluster-config-file nodes-6379.conf

# Cluster node timeout is the amount of milliseconds a node must be unreachable
# for it to be considered in failure state.
# Most other internal time limits are multiple of the node timeout.
#
# cluster-node-timeout 15000

# A slave of a failing master will avoid to start a failover if its data
# looks too old.
#
# There is no simple way for a slave to actually have an exact measure of
# its "data age", so the following two checks are performed:
#
# 1) If there are multiple slaves able to failover, they exchange messages
#    in order to try to give an advantage to the slave with the best
#    replication offset (more data from the master processed).
#    Slaves will try to get their rank by offset, and apply to the start
#    of the failover a delay proportional to their rank.
#
# 2) Every single slave computes the time of the last interaction with
#    its master. This can be the last ping or command received (if the master
#    is still in the "connected" state), or the time that elapsed since the
#    disconnection with the master (if the replication link is currently down).
#    If the last interaction is too old, the slave will not try to failover
#    at all.
#
# The point "2" can be tuned by user. Specifically a slave will not perform
# the failover if, since the last interaction with the master, the time
# elapsed is greater than:
#
#   (node-timeout * slave-validity-factor) + repl-ping-slave-period
#
# So for example if node-timeout is 30 seconds, and the slave-validity-factor
# is 10, and assuming a default repl-ping-slave-period of 10 seconds, the
# slave will not try to failover if it was not able to talk with the master
# for longer than 310 seconds.
#
# A large slave-validity-factor may allow slaves with too old data to failover
# a master, while a too small value may prevent the cluster from being able to
# elect a slave at all.
#
# For maximum availability, it is possible to set the slave-validity-factor
# to a value of 0, which means, that slaves will always try to failover the
# master regardless of the last time they interacted with the master.
# (However they'll always try to apply a delay proportional to their
# offset rank).
#
# Zero is the only value able to guarantee that when all the partitions heal
# the cluster will always be able to continue.
#
# cluster-slave-validity-factor 10

# Cluster slaves are able to migrate to orphaned masters, that are masters
# that are left without working slaves. This improves the cluster ability
# to resist to failures as otherwise an orphaned master can't be failed over
# in case of failure if it has no working slaves.
#
# Slaves migrate to orphaned masters only if there are still at least a
# given number of other working slaves for their old master. This number
# is the "migration barrier". A migration barrier of 1 means that a slave
# will migrate only if there is at least 1 other working slave for its master
# and so forth. It usually reflects the number of slaves you want for every
# master in your cluster.
#
# Default is 1 (slaves migrate only if their masters remain with at least
# one slave). To disable migration just set it to a very large value.
# A value of 0 can be set but is useful only for debugging and dangerous
# in production.
#
# cluster-migration-barrier 1

# By default Redis Cluster nodes stop accepting queries if they detect there
# is at least an hash slot uncovered (no available node is serving it).
# This way if the cluster is partially down (for example a range of hash slots
# are no longer covered) all the cluster becomes, eventually, unavailable.
# It automatically returns available as soon as all the slots are covered again.
#
# However sometimes you want the subset of the cluster which is working,
# to continue to accept queries for the part of the key space that is still
# covered. In order to do so, just set the cluster-require-full-coverage
# option to no.
#
# cluster-require-full-coverage yes

# In order to setup your cluster make sure to read the documentation
# available at http://redis.io web site.

修改完之后按下ESC 键，再按下 :wq!保存突出。同理，s2中的redis也是这样修改的但是，需要修改一下端口号，不能喝上面的端口号重复，s2中的端口号为6390。

使用相同的方式修改第二台上redis的配置：只不过在该台机器上只有一个redis服务(节点)

上面这两台服务器中的三个redis服务地址分别为：192.168.0.109:6379 192.168.0.109:6390 192.168.0.111:6379，在进行第三部的时候要用到。

（3）第三台机器的配置

上面的两步中我们共开起了三台主redis节点，所以在第三台服务器上我们也要开启三台从节点，结果如下：

其中s1、s2、s3中文件和上面的一样，即三台从的redis节点。我们需要一个一个安装上面的配置修改redis.conf文件，只不过需要注意，三个节点的端口号是不一样的。s1、s2、s3的端口号分别是:6379 6380 6381

到现在个个redis节点的配置文件也修改好了，下面我们要分别启动s1 s2 s3 和上面的三个主redis服务了~~~~~~

接下来，这三个服务都会生产一个这样的文件：

因为redis-trib.rb是ruby写的，不信可以打开看看。而在我们的Ubuntu16.04.1上是有ruby的环境的，但是还是强烈建议执行以下下面的指令安装ruby，同时还要安装 ruby的Redis库，不过没关系，我们可以按照下面的步骤安装。

安装Redis-Cluster的依赖库(可能在安装依赖库的时候特别慢，可以使用加速器，我就不在这里说了，你懂的)
- 安装Ruby
  
  sudo apt-get install ruby
- 安装Redis.gem
  
  sudo gem intall redis

耐心等待，因为很慢的(#^.^#)。安装好之后，执行下面图中划的命令：

解释：./redis-trib.rb create --replicas 1 192.168.0.109:6379 192.168.0.109:6390 192.168.0.110:6379 192.168.0.111:6379 192.168.0.111:6380 192.168.0.111:6381

这些IP都是上面redis服务的IP，注意他们之间是有空格分开的。

如果出现上面的信息说明安装成功了！！！

其中：192.168.0.109:6379、192.168.0.110:6379/192.168.0.111:6379是主，192.168.0.111:6380/192.168.0.109:6390、192.168.0.111:6381是从的。

（4）测试是否成功

在到192.168.0.110:6379中看看有没有值：

看到没，值同步过来了！！！！

三、面对Redis-ClusterC#该如何操作

step1：使用VS2017新建一个控制台程序

step2: Install-Package StackExchange.Redis

step3:编写代码：

 1 using StackExchange.Redis;
 2 using System;
 3 using System.Collections.Generic;
 4 using System.Linq;
 5 using System.Text;
 6 using System.Threading.Tasks;
 7 
 8 namespace LinuxRedisCluster
 9 {
10     class Program
11     {
12         static void Main(string[] args)
13         {
14             using (ConnectionMultiplexer redis = ConnectionMultiplexer.Connect("192.168.0.109:6379,192.168.0.109:6390,192.168.0.110:6379,192.168.0.111:6379,192.168.0.111:6380,192.168.0.111:6381"))
15             {
16 
17                 IDatabase db = redis.GetDatabase();
18                 for (int i = 0; i < 1000; i++)
19                 {
20                     db.StringSet("name"+i, "guozheng"+i);
21                 }
22                 
23 
24                 //var myname = db.StringGet("name");
25                // Console.WriteLine(myname);
26             }
27 
28             Console.ReadKey();
29         }
30     }
31 }