1如果将全部数据都保存到一台redis中，如果该服务器损坏，则影响全部的服务
2使用单台redis内存设定一般不超过1G,但是有些业务数据量很大。如果不修改内存则无法存储。
改进方案:参用Redis分片技术实现。
优点:
1使用redis分片可以实现内存数据的动态扩容。
2使用分片，每台redis节点中尽可能保存1/n的数据量。防止数据的丢失。
3对于用户而言，整个redis的分片就是一个服务。

分片搭建

[root@localhost redis-3.2.8]# redis-cli shutdown
[root@localhost redis-3.2.8]# ls
00-RELEASENOTES  COPYING   INSTALL    README.md    runtest           sentinel.conf  utils
BUGS             deps      Makefile   redis.conf   runtest-cluster   src
CONTRIBUTING     dump.rdb  MANIFESTO  redis.conf~  runtest-sentinel  tests
[root@localhost redis-3.2.8]# mkdir shards
[root@localhost redis-3.2.8]# ls
00-RELEASENOTES  COPYING   INSTALL    README.md    runtest           sentinel.conf  tests
BUGS             deps      Makefile   redis.conf   runtest-cluster   shards         utils
CONTRIBUTING     dump.rdb  MANIFESTO  redis.conf~  runtest-sentinel  src

复制配置文件
将redis.conf文件复制到shards中，并且复制3份名称为
redis-6379.conf/redis-6380.conf/redis-6381.conf

[root@localhost redis-3.2.8]# cp redis.conf shards/redis-6379.conf
[root@localhost redis-3.2.8]# cp redis.conf shards/redis-6380.conf
[root@localhost redis-3.2.8]# cp redis.conf shards/redis-6381.conf

[root@localhost redis-3.2.8]# cd shards
[root@localhost shards]# ls
redis-6379.conf  redis-6380.conf  # Accept connections on the specified port, default is 6379 (IANA #815344).
# If port 0 is specified Redis will not listen on a TCP socket.

修改端口号，启动redis
说明：分别修改6380和6381的配置文件为指定端口

[root@localhost shards]# vim redis-6380.conf
port 6380
[root@localhost shards]# vim redis-6381.conf
# 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 6381

[root@localhost shards]# redis-server redis-6379.conf
[root@localhost shards]# redis-server redis-6380.conf
[root@localhost shards]# redis-server redis-6381.conf
[root@localhost shards]# 
[root@localhost shards]# ps -ef |grep redis
root      4395     1  0 20:01 ?        00:00:02 gedit /usr/local/src/redis-3.2.8/redis.conf
root      4628     1  0 20:45 ?        00:00:00 redis-server *:6379         
root      4632     1  0 20:45 ?        00:00:00 redis-server *:6380         
root      4636     1  0 20:45 ?        00:00:00 redis-server *:6381         
root      4641  3425  0 20:45 pts/1    00:00:00 grep redis

package test;

import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

import redis.clients.jedis.JedisPoolConfig;
import redis.clients.jedis.JedisShardInfo;
import redis.clients.jedis.ShardedJedis;
import redis.clients.jedis.ShardedJedisPool;

public class TestShardRedis {
    @Test
    public void testShard(){
        //创建分片的对象1.poolConfig标识池的大小，2.shards redis分片的节点信息
        JedisPoolConfig poolConfig=new JedisPoolConfig();
        poolConfig.setMaxTotal(1000);
        poolConfig.setTestOnBorrow(true);//获取链接是先检测，如果不行换一个
        List<JedisShardInfo> shards=new ArrayList<JedisShardInfo>();
        shards.add(new JedisShardInfo("192.168.161.135",6379));
        shards.add(new JedisShardInfo("192.168.161.135",6380));
        shards.add(new JedisShardInfo("192.168.161.135",6381));
        ShardedJedisPool pool=new ShardedJedisPool(poolConfig, shards);
        //获取redis连接
        ShardedJedis jedis = pool.getResource();
        jedis.set("shards", "保存分片的数据");
        System.out.println(jedis.get("shards"));
        //将连接还回池中
        pool.returnResource(jedis);
        pool.close();
    }

}