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。
(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。
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:
(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。
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!!!!
step1:使用VS2017新建一个控制台程序
step2: Install-Package StackExchange.Redis
step3:编写代码:
- using StackExchange.Redis;
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- using System.Threading.Tasks;
- namespace LinuxRedisCluster
- {
- class Program
- {
- static void Main(string[] args)
- {
- 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"))
- {
- IDatabase db = redis.GetDatabase();
- for (int i = 0; i < 1000; i++)
- {
- db.StringSet("name"+i, "guozheng"+i);
- }
- //var myname = db.StringGet("name");
- // Console.WriteLine(myname);
- }
- Console.ReadKey();
- }
- }
- }
step4:查看结果:
四、总结:
关于redis如何集群的详细信息,可以参考Redis手册:集群教程
也可以参考下面这些博客:
http://www.cnblogs.com/huangxincheng/p/5615037.html
http://www.cnblogs.com/piscesLoveCc/p/5779795.html
觉得可以的话,希望点下推荐哈~你们的推荐是我的动力。
来源: http://www.cnblogs.com/runningsmallguo/p/7588529.html