Redis3 正式支持了 cluster，是為了解決構建redis集群時的諸多不便
（1）像操作單個redis一樣操作key，不用操心key在哪個節點上
（2）在線動態添加、刪除redis節點，不用停止服務
（3）根據節點性能，動態分配不同數量的key到不同redis節點
（4）每個節點都配有slave，並自動監測和切換
Redis3 cluster 中增加了一個重要概念：
hash slot（哈希槽），共有16384個slot
key不是直接放入redis中了，而是放入slot中，再把slot放入redis中
根據key的hash值計算其所在的slot，再根據slot和redis節點的對應關系，找到此slot所在的節點，然后到這個節點對key進行操作
例如現有3個redis節點，每個節點各負責一半數量的slot，16384/3 = 5461個現在想添加一個redis節點，可以從 節點 1、節點 2、節點 3 中各拿出一部分的slot，移到新節點
每個redis節點中的slot數量可以不一致，根據節點性能適當分配
進入集群需要用redis -c -p 7000 -c是enable cluster p指定進入端口
搭建集群遇到的問題：
由於教程里面給出的集群的地址是127.0.0.1:7000、......，在java程序訪問的時候是無法獲取節點信息的，所以我需要重新搭建集群，然后停掉所有節點，重新搭建的時候，報出了如下錯誤，可知是因為有些配置文件以及數據沒有刪除。將其全部刪除干凈即可。
[ERR] Node 172.168.63.202:7001 is not empty.
Either the nodealready knows other nodes (check with CLUSTER NODES) or contains some key in database 0.
find / -name dump.rdb
rm -f /usr/redis/cluster/7002/redis7002/src/dump.rdb
rm -f /usr/redis/cluster/7004/redis7004/src/dump.rdb
rm -f /usr/redis/cluster/7005/redis7005/src/dump.rdb
rm -f /usr/redis/cluster/7001/redis7001/src/dump.rdb
rm -f /usr/redis/cluster/7000/redis7000/src/dump.rdb
rm -f /usr/redis/cluster/7003/redis7003/src/dump.rdb
rm -f /usr/redis/master/redis-3.0.7/src/dump.rdb
find / -name dump.rdb
find / -name appendonly.aof
rm -f /usr/redis/cluster/7002/redis7002/src/appendonly.aof
rm -f /usr/redis/cluster/7004/redis7004/src/appendonly.aof
rm -f /usr/redis/cluster/7005/redis7005/src/appendonly.aof
rm -f /usr/redis/cluster/7001/redis7001/src/appendonly.aof
rm -f /usr/redis/cluster/7000/redis7000/src/appendonly.aof
rm -f /usr/redis/cluster/7003/redis7003/src/appendonly.aof
find / -name appendonly.aof
find / -name nodes.conf
rm -f /usr/redis/cluster/7002/redis7002/src/nodes.conf
rm -f /usr/redis/cluster/7004/redis7004/src/nodes.conf
rm -f /usr/redis/cluster/7005/redis7005/src/nodes.conf
rm -f /usr/redis/cluster/7001/redis7001/src/nodes.conf
rm -f /usr/redis/cluster/7000/redis7000/src/nodes.conf
rm -f /usr/redis/cluster/7003/redis7003/src/nodes.conf
find / -name nodes.conf
#創建集群
#!/bin/sh
cd /usr/redis/cluster/7000/redis7000/src/
./redis-server ../redis.conf
cd /usr/redis/cluster/7001/redis7001/src/
./redis-server ../redis.conf
cd /usr/redis/cluster/7002/redis7002/src/
./redis-server ../redis.conf
cd /usr/redis/cluster/7003/redis7003/src/
./redis-server ../redis.conf
cd /usr/redis/cluster/7004/redis7004/src/
./redis-server ../redis.conf
cd /usr/redis/cluster/7005/redis7005/src/
./redis-server ../redis.conf
cd /usr/redis/cluster/7000/redis7000/src/
./redis-trib.rb create --replicas 1 192.168.10.102:7000 192.168.10.102:7001 192.168.10.102:7002 192.168.10.102:7003 192.168.10.102:7004 192.168.10.102:7005
#集群啟動關閉：
#!/bin/sh
/usr/redis/cluster/7000/redis7000/src/redis-cli -p 7000 shutdown
/usr/redis/cluster/7001/redis7001/src/redis-cli -p 7001 shutdown
/usr/redis/cluster/7002/redis7002/src/redis-cli -p 7002 shutdown
/usr/redis/cluster/7003/redis7003/src/redis-cli -p 7003 shutdown
/usr/redis/cluster/7004/redis7004/src/redis-cli -p 7004 shutdown
/usr/redis/cluster/7005/redis7005/src/redis-cli -p 7005 shutdown
if [ $(ps -ef | grep -c redis | grep -cv grep) -gt 1 ]
then echo "集群關機失敗，請檢查節點"
else
echo "集群全部關閉，ok"
fi
//集群搭建教程 http://blog.csdn.net/yubinpll9110/article/details/51373890
這里創建6個redis節點，其中三個為主節點，三個為從節點。
redis和端口對應關系：
主服務器
127.0.0.1:7000
127.0.0.1:7001
127.0.0.1:7002從服務器：
127.0.0.1:7003
127.0.0.1:7004
127.0.0.1:7005
步驟：
1,下載redis。官網下載3.0.0版本，之前幾的版本不支持集群模式
下載地址：http://download.redis.io/releases/redis-3.0.0.tar.gz
2：上傳服務器，解壓，編譯
tar -zxvf redis-3.0.0-rc2.tar.gz
mv redis-3.0.0-rc2.tar.gz redis3.0
cd /usr/local/redis3.0
make & make install
3：創建集群需要的目錄並拷貝redis
mkdir -p /usr/local/cluster
mkdir -p /usr/local/cluster/7000
mkdir -p /usr/local/cluster/7001
mkdir -p /usr/local/cluster/7002
mkdir -p /usr/local/cluster/7003
mkdir -p /usr/local/cluster/7004
mkdir -p /usr/local/cluster/7005
cp -rf /usr/local/redis3.0/* /usr/local/cluster/7000/
cp -rf /usr/local/redis3.0/* /usr/local/cluster/7001/
cp -rf /usr/local/redis3.0/* /usr/local/cluster/7002/
cp -rf /usr/local/redis3.0/* /usr/local/cluster/7003/
cp -rf /usr/local/redis3.0/* /usr/local/cluster/7004/
cp -rf /usr/local/redis3.0/* /usr/local/cluster/7005/
4：修改配置文件redis.conf
vi /usr/local/cluster/7000/redis.conf
##修改配置文件中的下面選項
port 7000
daemonize yes
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
appendonly yes
#同樣再對其它配置文件進行修改
vi /usr/local/cluster/7001/redis.conf
vi /usr/local/cluster/7002/redis.conf
vi /usr/local/cluster/7003/redis.conf
vi /usr/local/cluster/7004/redis.conf
vi /usr/local/cluster/7005/redis.conf
##注意：不同的目錄配置不同的redis.conf中的port
5：啟動6個redis
cd /usr/local/cluster/7000/src
redis-server ../redis.conf
cd /usr/local/cluster/7001/src
redis-server ../redis.conf
cd /usr/local/cluster/7002/src
redis-server ../redis.conf
cd /usr/local/cluster/7003/src
redis-server ../redis.conf
cd /usr/local/cluster/7004/src
redis-server ../redis.conf
cd /usr/local/cluster/7005/src
redis-server ../redis.conf
##啟動之后使用命令查看redis的啟動情況ps -ef|grep redis
6,創建redis集群
cd /usr/local/redis3.0/src
./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
6.1執行上面的命令的時候會報錯，因為是執行的的腳本，需要
錯誤內容：/usr/bin/env: ruby: No such file or directory
所以需要安裝ruby的環境，這里推薦使用yum install ruby
yum install ruby
6.2然后再執行第步的創建集群命令，還會報錯，提示缺少rubygems組件
錯誤內容：
./redis-trib.rb:24:in `require': no such file to load -- rubygems (LoadError)
from ./redis-trib.rb:24
yum install rubygems
6.3再次執行第步的命令，還會報錯，提示不能加載redis，是因為缺少redis的接口
錯誤內容：
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require': no such file to load -- redis (LoadError)
from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from ./redis-trib.rb:25
gem install redis
這里可能無法安裝,因為無法連接gem服務器：
[@zw_22_90 src]# gem install redis --version 3.0.0
ERROR: Could not find a valid gem 'redis' (= 3.0.0) in any repository
ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError)
如何使用？
$ gem sources --remove https://rubygems.org/ $ gem sources -a https://ruby.taobao.org/ $ gem sources -l *** CURRENT SOURCES *** https://ruby.taobao.org # 請確保只有 ruby.taobao.org $ gem install rails
6.4 再次執行第步的命令，正常執行
輸入yes，然后配置完成。
[@zw_22_90 src]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
>>> Creating cluster
Connecting to node 127.0.0.1:7000: OK
Connecting to node 127.0.0.1:7001: OK
Connecting to node 127.0.0.1:7002: OK
Connecting to node 127.0.0.1:7003: OK
Connecting to node 127.0.0.1:7004: OK
Connecting to node 127.0.0.1:7005: OK
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
127.0.0.1:7000
127.0.0.1:7001
127.0.0.1:7002
Adding replica 127.0.0.1:7003 to 127.0.0.1:7000
Adding replica 127.0.0.1:7004 to 127.0.0.1:7001
Adding replica 127.0.0.1:7005 to 127.0.0.1:7002
M: 2022f24d581b4a7c3342e3245c32927cbd5ec16d 127.0.0.1:7000
slots:0-5460 (5461 slots) master
M: 37b7008f80f8c21a698da8cb1f1b32db8c0c415c 127.0.0.1:7001
slots:5461-10922 (5462 slots) master
M: ac6dc5fa96e856b34c1ba4c3814394e4ebb698dd 127.0.0.1:7002
slots:10923-16383 (5461 slots) master
S: b5b76d70bbb0dbf3e7df8a38f1259e95e2054721 127.0.0.1:7003
replicates 2022f24d581b4a7c3342e3245c32927cbd5ec16d
S: 6881f8fef9c25da486f320ebf2ead39c1502db4c 127.0.0.1:7004
replicates 37b7008f80f8c21a698da8cb1f1b32db8c0c415c
S: f090526d32cced97731eef2a2e1722a7bac7d9ea 127.0.0.1:7005
replicates ac6dc5fa96e856b34c1ba4c3814394e4ebb698dd
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join...
>>> Performing Cluster Check (using node 127.0.0.1:7000)
M: 2022f24d581b4a7c3342e3245c32927cbd5ec16d 127.0.0.1:7000
slots:0-5460 (5461 slots) master
M: 37b7008f80f8c21a698da8cb1f1b32db8c0c415c 127.0.0.1:7001
slots:5461-10922 (5462 slots) master
M: ac6dc5fa96e856b34c1ba4c3814394e4ebb698dd 127.0.0.1:7002
slots:10923-16383 (5461 slots) master
M: b5b76d70bbb0dbf3e7df8a38f1259e95e2054721 127.0.0.1:7003
slots: (0 slots) master
replicates 2022f24d581b4a7c3342e3245c32927cbd5ec16d
M: 6881f8fef9c25da486f320ebf2ead39c1502db4c 127.0.0.1:7004
slots: (0 slots) master
replicates 37b7008f80f8c21a698da8cb1f1b32db8c0c415c
M: f090526d32cced97731eef2a2e1722a7bac7d9ea 127.0.0.1:7005
slots: (0 slots) master
replicates ac6dc5fa96e856b34c1ba4c3814394e4ebb698dd
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
至此redis集群即搭建成功！
7，redis-cli命令進入集群環境
[@zw_22_90 src]# redis-cli -c -p 7000
127.0.0.1:7000> quit;