1：环境说明，首先说一下要做的事情，我们要迁移redis集群槽位，现有redis集群环境如下
172,16.128.240:7003
172,16.128.240:7004
172,16.128.241:7003
172,16.128.241:7004
172,16.128.242:7003
172,16.128.242:7004
我们看一下集群的基本信息：
172,16.128.240:7003> cluster nodes
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528448456000 4 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528448456095 2 connected 10923-16383
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 myself,master - 0 1528448456000 0 connected 0-5461
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528448457096 5 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528448455000 1 connected 5462-10922
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528448458098 3 connected
2：在172,16.128.242上创建7013和7014实例
[root@mxq-ss1 redis7014]# redis-server /home/redis/redis7013/redis7013.conf
[root@mxq-ss1 redis7014]# redis-server /home/redis/redis7014/redis7014.conf
[root@mxq-ss1 redis7004]# ps -ef|grep redis
root 41550 1 0 01:21 ? 00:00:09 redis-server 172,16.128.242:7003 [cluster]
root 41559 1 0 01:22 ? 00:00:09 redis-server 172,16.128.242:7004 [cluster]
root 45182 1 0 04:54 ? 00:00:00 redis-server 172,16.128.242:7013 [cluster]
root 45187 1 0 04:54 ? 00:00:00 redis-server 172,16.128.242:7014 [cluster]
root 45192 34163 0 04:54 pts/3 00:00:00 grep --color=auto redis
3：正式进行热拓展测试（以下脚本将要应用到生产机房，请审视）
（1）server172,16.128.240
[root@mxq-ss3 data]# redis-cli -h 172,16.128.240 -p 7003 -a Rmbe7q3btATOE2Xyvmv
172,16.128.240:7003> cluster nodes
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528449386696 4 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528449385694 2 connected 10923-16383
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 myself,master - 0 1528449384000 0 connected 0-5461
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528449384692 5 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528449384000 1 connected 5462-10922
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528449384000 3 connected
172,16.128.240:7003> cluster info
cluster_state:ok
cluster_slots_assigned:16384
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:6
cluster_size:3
cluster_current_epoch:5
cluster_my_epoch:0
cluster_stats_messages_ping_sent:4212
cluster_stats_messages_pong_sent:4031
cluster_stats_messages_meet_sent:5
cluster_stats_messages_sent:8248
cluster_stats_messages_ping_received:4031
cluster_stats_messages_pong_received:4217
cluster_stats_messages_received:8248
172,16.128.240:7003> cluster meet 172,16.128.242 7013
OK
172,16.128.240:7003> cluster meet 172,16.128.242 7014
OK
172,16.128.240:7003> cluster nodes
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528449505892 4 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528449506000 2 connected 10923-16383
c73b4e70468d091e40123122ce140422f027d0d2 172,16.128.242:7013@17013 master - 0 1528449506593 6 connected
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 myself,master - 0 1528449503000 0 connected 0-5461
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528449504000 5 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528449504891 1 connected 5462-10922
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528449505000 3 connected
bd40901964330046ff5752fe62c7e11abba7ab06 172,16.128.242:7014@17014 master - 0 1528449506892 7 connected
172,16.128.240:7003> cluster info
cluster_state:ok
cluster_slots_assigned:16384
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:8
cluster_size:3
cluster_current_epoch:7
cluster_my_epoch:0
cluster_stats_messages_ping_sent:4341
cluster_stats_messages_pong_sent:4147
cluster_stats_messages_meet_sent:7
cluster_stats_messages_sent:8495
cluster_stats_messages_ping_received:4147
cluster_stats_messages_pong_received:4348
cluster_stats_messages_received:8495
（2）执行过脚本如下：
[root@mxq-ss3 data]# redis-cli -h 172,16.128.240 -p 7003 -a Rmbe7q3btATOE2Xyvmv
172,16.128.240:7003> cluster nodes
172,16.128.240:7003> cluster info
172,16.128.240:7003> cluster meet 172,16.128.242 7013
OK
172,16.128.240:7003> cluster meet 172,16.128.242 7014
OK
172,16.128.240:7003> cluster nodes
172,16.128.240:7003> cluster info
我们从上面信息已经看出已经将新建节点加入到了集群当中。下面开始将新加入的节点作为主从 server172,16.128.242
[root@mxq-ss1 redis7014]# redis-cli -h 172,16.128.242 -p 7014 -a Rmbe7q3btATOE2Xyvmv
172,16.128.242:7014> cluster replicate c73b4e70468d091e40123122ce140422f027d0d2
OK
172,16.128.242:7014> CLUSTER NODES
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528449970993 1 connected
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 master - 0 1528449971994 0 connected 0-5461
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528449968000 0 connected
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528449972000 2 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528449972996 1 connected 5462-10922
c73b4e70468d091e40123122ce140422f027d0d2 172,16.128.242:7013@17013 master - 0 1528449970000 6 connected
bd40901964330046ff5752fe62c7e11abba7ab06 172,16.128.242:7014@17014 myself,slave c73b4e70468d091e40123122ce140422f027d0d2 0 1528449971000 7 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528449969000 2 connected 10923-16383
4:执行完以后进行热拓展
先说明一下现在有三台主从，做热拓展的话，每个槽位都要迁移出1365个槽位到172,16.128.242:7013的redis实例上。以下是迁移步骤 执行机器：172,16.128.240
执行以前，我们要确定以下配置文件
vi /usr/local/rvm/gems/ruby-2.4.1/gems/redis-4.0.1/lib/redis/client.rb
里面配置和redis的配置要一致，不然连不上redis报错。这个要确认。下面执行迁移过程
[root@mxq-ss3 ~]# redis-trib.rb reshard 172,16.128.240:7003
How many slots do you want to move (from 1 to 16384)? 1364
What is the receiving node ID? 363ecec54c92c2548dcab016146bdb4c104e5e84
Please enter all the source node IDs.
Type 'all' to use all the nodes as source nodes for the hash slots.
Type 'done' once you entered all the source nodes IDs.
Source node #1:c73b4e70468d091e40123122ce140422f027d0d2
Source node #2:done
查看节点信息：
172,16.128.240:7003> cluster nodes
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528535455177 4 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528535457181 2 connected 10923-16383
c73b4e70468d091e40123122ce140422f027d0d2 172,16.128.242:7013@17013 master - 0 1528535456180 6 connected
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 myself,master - 0 1528535455000 0 connected 0-5461
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528535455000 5 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528535453172 1 connected 5462-10922
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528535453000 3 connected
bd40901964330046ff5752fe62c7e11abba7ab06 172,16.128.242:7014@17014 slave c73b4e70468d091e40123122ce140422f027d0d2 0 1528535453000 7 connected
172,16.128.240:7003> cluster nodes
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528535856000 4 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528535852000 2 connected 10923-16383
c73b4e70468d091e40123122ce140422f027d0d2 172,16.128.242:7013@17013 master - 0 1528535856884 8 connected 0-1364
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 myself,master - 0 1528535854000 0 connected 1365-5461
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528535855883 5 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528535856000 1 connected 5462-10922
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528535855000 3 connected
bd40901964330046ff5752fe62c7e11abba7ab06 172,16.128.242:7014@17014 slave c73b4e70468d091e40123122ce140422f027d0d2 0 1528535854000 8 connected
发现执行完毕，已经迁移了。接下来同样方式迁移其他两台master相同槽位到新节点上。 执行完查看节点信息，发现已经完全迁移上去了。
[root@mxq-ss3 ~]# redis-cli -h 172,16.128.240 -p 7003 -a ***********cluster nodes
8ea64a0049e0b193296aeba868391e7b009ed562 172,16.128.241:7004@17004 slave 7a35e29ebffb7fd42a9533811b8fcf67955635f2 0 1528536351000 4 connected
1cbccbfa9a6ee62d2f744af14fddfe97cc491926 172,16.128.242:7003@17003 master - 0 1528536352764 2 connected 12287-16383
c73b4e70468d091e40123122ce140422f027d0d2 172,16.128.242:7013@17013 master - 0 1528536349759 8 connected 0-1364 5462-6825 10923-12286
d4fac62706aa4def7611a495676ebc2151fc07ba 172,16.128.240:7003@17003 myself,master - 0 1528536351000 0 connected 1365-5461
3801a25ac04c7e2c610c1df9588c107e0ed62fa1 172,16.128.242:7004@17004 slave 1cbccbfa9a6ee62d2f744af14fddfe97cc491926 0 1528536349000 5 connected
7a35e29ebffb7fd42a9533811b8fcf67955635f2 172,16.128.241:7003@17003 master - 0 1528536350759 1 connected 6826-10922
7f2dbd47e72c7b15b160e0f11d9f0ef86f225c27 172,16.128.240:7004@17004 slave d4fac62706aa4def7611a495676ebc2151fc07ba 0 1528536351761 3 connected
bd40901964330046ff5752fe62c7e11abba7ab06 172,16.128.242:7014@17014 slave c73b4e70468d091e40123122ce140422f027d0d2 0 1528536350000 8 connected
整体迁移脚本如下：
脚本步骤：
脚本步骤： 11：server10：server172,16.128.240上执行
[root@mxq-ss3 data]# redis-cli -h 172,16.128.240 -p 7003 -a Rmbe7q3btATOE2Xyvmv
172,16.128.240:7003> cluster nodes
172,16.128.240:7003> cluster info
172,16.128.240:7003> cluster meet 172,16.128.242 7013
OK
172,16.128.240:7003> cluster meet 172,16.128.242 7014
OK
172,16.128.240:7003> cluster nodes
172,16.128.240:7003> cluster info
新加入节点做主从：
[root@mxq-ss1 redis7014]# redis-cli -h 172,16.128.242 -p 7014 -a Rmbe7q3btATOE2Xyvmv
172,16.128.242:7014> cluster replicate c73b4e70468d091e40123122ce140422f027d0d2
OK
172,16.128.242:7014> CLUSTER NODES
下面进行迁移（注意我们要执行三次，手动从240,241,242上7003实例迁移1364个slot到新实例上，并且每次迁移完成都要查看一下节点状态）：
[root@mxq-ss3 ~]# redis-trib.rb reshard 172,16.128.240:7003
How many slots do you want to move (from 1 to 16384)? 1364
What is the receiving node ID? 363ecec54c92c2548dcab016146bdb4c104e5e84
Please enter all the source node IDs.
Type 'all' to use all the nodes as source nodes for the hash slots.
Type 'done' once you entered all the source nodes IDs.
Source node #1:c73b4e70468d091e40123122ce140422f027d0d2
Source node #2:done
[root@mxq-ss3 ~]# redis-cli -h 172,16.128.240 -p 7003 -a ***********cluster nodes
[root@mxq-ss3 ~]# redis-cli -h 172,16.128.240 -p 7003 -a ***********cluster info