Redis热迁移实战总结

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Redis cluster使用 slots 来分配集群中的资源，因此官方提供了热迁移 slots 的方案，以便于迁移 redis cluster 节点中的信息。此方案不仅可以使用于节点迁移，也可以根据资源的不同，配置不同的 slots 数量。

集群原环境：

主机IP： 192.168.170.101

集群节点端口：10001-10006

集群当前主备关系：

迁移需求：现在有节点 redis007, 需要将 redis002 替换掉

迁移步骤：

1. 首先验证环境当前的配置：

由上可以看出节点信息如下：

10001M<-10004S  slots=5461

10002M<-10005S      slots=5462

10003M<-10006S      slots=5461

2. 现在来插入 10W 条数据

from rediscluster import StrictRedisCluster

redis_nodes = [

        {“host”: “192.168.170.101”, “port”: “10001”},

        {“host”: “192.168.170.101”, “port”: “10002”},

        {“host”: “192.168.170.101”, “port”: “10003”},

        {“host”: “192.168.170.101”, “port”: “10004”},

        {“host”: “192.168.170.101”, “port”: “10005”},

        {“host”: “192.168.170.101”, “port”: “10006”}

    ]

redis_conn = StrictRedisCluster(startup_nodes=redis_nodes, decode_responses=True)

for key in range(0, 100000):

    print key

    value = key

    key = ‘zhang%s’ % key

    redis_conn.set(key, value)

3. 启动 redis007，并将redis007 加入集群环境：

./redis-server redis007.conf

[root@lab001 redis]# redis-trib.rb add-node 192.168.170.101:10007 192.168.170.101:10001

>>> Adding node 192.168.170.101:10007 to cluster 192.168.170.101:10001

>>> Performing Cluster Check (using node 192.168.170.101:10001)

M: b30fdabd07a4bef611c160828965b91a1cdd462a 192.168.170.101:10001

  slots:0-5460 (5461 slots) master

  1 additional replica(s)

S: 74805544792cc22f09af941fa117b2974c9c0abf 192.168.170.101:10005

  slots: (0 slots) slave

  replicates 6036af6afc6567b74ce2fecc734a2d3908d561d1

M: 9c6a98926b23585e2eeb49ae17cc77521041d3ed 192.168.170.101:10003

  slots:10923-16383 (5461 slots) master

  1 additional replica(s)

S: 57a2e7313b952b38e32d6a1030d4812ea4decb5f 192.168.170.101:10006

  slots: (0 slots) slave

  replicates 9c6a98926b23585e2eeb49ae17cc77521041d3ed

S: 58b7b25501fdba04aef9b8cb47edef89092f10a7 192.168.170.101:10004

  slots: (0 slots) slave

  replicates b30fdabd07a4bef611c160828965b91a1cdd462a

M: 6036af6afc6567b74ce2fecc734a2d3908d561d1 192.168.170.101:10002

  slots:5461-10922 (5462 slots) master

  1 additional replica(s)

[OK] All nodes agree about slots configuration.

>>> Check for open slots…

>>> Check slots coverage…

[OK] All 16384 slots covered.

>>> Send CLUSTER MEET to node 192.168.170.101:10007 to make it join the cluster.

[OK] New node added correctly.

4. 查看当前节点状态信息

[root@lab001 redis]# redis-trib.rb check 192.168.170.101:10001

>>> Performing Cluster Check (using node 192.168.170.101:10001)

M: b30fdabd07a4bef611c160828965b91a1cdd462a 192.168.170.101:10001

  slots:0-5460 (5461 slots) master

  1 additional replica(s)

M: 7c1a0acf84b2cf08876036b07518fb8f2ea9b8f8 192.168.170.101:10007

  slots: (0 slots) master

  0 additional replica(s)

S: 74805544792cc22f09af941fa117b2974c9c0abf 192.168.170.101:10005

  slots: (0 slots) slave

  replicates 6036af6afc6567b74ce2fecc734a2d3908d561d1

M: 9c6a98926b23585e2eeb49ae17cc77521041d3ed 192.168.170.101:10003

  slots:10923-16383 (5461 slots) master

  1 additional replica(s)

S: 57a2e7313b952b38e32d6a1030d4812ea4decb5f 192.168.170.101:10006

  slots: (0 slots) slave

  replicates 9c6a98926b23585e2eeb49ae17cc77521041d3ed

S: 58b7b25501fdba04aef9b8cb47edef89092f10a7 192.168.170.101:10004

  slots: (0 slots) slave

  replicates b30fdabd07a4bef611c160828965b91a1cdd462a

M: 6036af6afc6567b74ce2fecc734a2d3908d561d1 192.168.170.101:10002

  slots:5461-10922 (5462 slots) master

  1 additional replica(s)

[OK] All nodes agree about slots configuration.

>>> Check for open slots…

>>> Check slots coverage…

[OK] All 16384 slots covered.

5. 由上可以发现，redis007添加到节点当中，但当前未分配任何 slots，这一步把redis002 的slots完全迁移到redis007

由于过程较长，这里不再输出全部过程

[root@lab001 redis]# redis-trib.rb reshard –from 6036af6afc6567b74ce2fecc734a2d3908d561d1 –to 7c1a0acf84b2cf08876036b07518fb8f2ea9b8f8 –slots 5462 –yes 192.168.170.101:10001

………………

Moving slot 10911 from 192.168.170.101:10002 to 192.168.170.101:10007: …..

Moving slot 10912 from 192.168.170.101:10002 to 192.168.170.101:10007: ……….

Moving slot 10913 from 192.168.170.101:10002 to 192.168.170.101:10007: ……

Moving slot 10914 from 192.168.170.101:10002 to 192.168.170.101:10007: …….

Moving slot 10915 from 192.168.170.101:10002 to 192.168.170.101:10007: …..

Moving slot 10916 from 192.168.170.101:10002 to 192.168.170.101:10007: …..

Moving slot 10917 from 192.168.170.101:10002 to 192.168.170.101:10007: …

Moving slot 10918 from 192.168.170.101:10002 to 192.168.170.101:10007: ……..

Moving slot 10919 from 192.168.170.101:10002 to 192.168.170.101:10007: …..

Moving slot 10920 from 192.168.170.101:10002 to 192.168.170.101:10007: …….

Moving slot 10921 from 192.168.170.101:10002 to 192.168.170.101:10007: ..

Moving slot 10922 from 192.168.170.101:10002 to 192.168.170.101:10007: ……….

6. 再次查看当前节点信息

[root@lab001 redis]# redis-trib.rb check 192.168.170.101:10001

>>> Performing Cluster Check (using node 192.168.170.101:10001)

M: b30fdabd07a4bef611c160828965b91a1cdd462a 192.168.170.101:10001

  slots:0-5460 (5461 slots) master

  1 additional replica(s)

M: 7c1a0acf84b2cf08876036b07518fb8f2ea9b8f8 192.168.170.101:10007

  slots:5461-10922 (5462 slots) master

  1 additional replica(s)

S: 74805544792cc22f09af941fa117b2974c9c0abf 192.168.170.101:10005

  slots: (0 slots) slave

  replicates 7c1a0acf84b2cf08876036b07518fb8f2ea9b8f8

M: 9c6a98926b23585e2eeb49ae17cc77521041d3ed 192.168.170.101:10003

  slots:10923-16383 (5461 slots) master

  1 additional replica(s)

S: 57a2e7313b952b38e32d6a1030d4812ea4decb5f 192.168.170.101:10006

  slots: (0 slots) slave

  replicates 9c6a98926b23585e2eeb49ae17cc77521041d3ed

S: 58b7b25501fdba04aef9b8cb47edef89092f10a7 192.168.170.101:10004

  slots: (0 slots) slave

  replicates b30fdabd07a4bef611c160828965b91a1cdd462a

M: 6036af6afc6567b74ce2fecc734a2d3908d561d1 192.168.170.101:10002

  slots: (0 slots) master

  0 additional replica(s)

[OK] All nodes agree about slots configuration.

>>> Check for open slots…

>>> Check slots coverage…

[OK] All 16384 slots covered.

由此可以发现，redis002的所有 slots 迁移到 redis007 完毕，并且 redis005 自动将主从关系从 002 转移到了007

7. 最后来验证下数据的完整性

from rediscluster import StrictRedisCluster 

redis_nodes = [

        {“host”: “192.168.170.101”, “port”: “10001”},

        {“host”: “192.168.170.101”, “port”: “10002”},

        {“host”: “192.168.170.101”, “port”: “10003”},

        {“host”: “192.168.170.101”, “port”: “10004”},

        {“host”: “192.168.170.101”, “port”: “10005”},

        {“host”: “192.168.170.101”, “port”: “10006”}

    ]

redis_conn = StrictRedisCluster(startup_nodes=redis_nodes, decode_responses=True)

for key in range(0, 100000):

    #value = key

    key = ‘zhang%s’ % key

    #redis_conn.set(key, value)

    print redis_conn.get(key)

执行完毕，数据较验完成，数据完成完整迁移

8. 最后，将 redis002 从集群中移除

[root@lab001 redis]# redis-trib.rb del-node 192.168.170.101:10001 6036af6afc6567b74ce2fecc734a2d3908d561d1

>>> Removing node 6036af6afc6567b74ce2fecc734a2d3908d561d1 from cluster 192.168.170.101:10001

>>> Sending CLUSTER FORGET messages to the cluster…

>>> SHUTDOWN the node.

[2]  Done                    ./redis001/bin/redis-server redis00$i/redis00$i.conf

9. 再次查看集群状态

[root@lab001 redis]# redis-trib.rb check 192.168.170.101:10001

>>> Performing Cluster Check (using node 192.168.170.101:10001)

M: b30fdabd07a4bef611c160828965b91a1cdd462a 192.168.170.101:10001

  slots:0-5460 (5461 slots) master

  1 additional replica(s)

M: 7c1a0acf84b2cf08876036b07518fb8f2ea9b8f8 192.168.170.101:10007

  slots:5461-10922 (5462 slots) master

  1 additional replica(s)

S: 74805544792cc22f09af941fa117b2974c9c0abf 192.168.170.101:10005

  slots: (0 slots) slave

  replicates 7c1a0acf84b2cf08876036b07518fb8f2ea9b8f8

M: 9c6a98926b23585e2eeb49ae17cc77521041d3ed 192.168.170.101:10003

  slots:10923-16383 (5461 slots) master

  1 additional replica(s)

S: 57a2e7313b952b38e32d6a1030d4812ea4decb5f 192.168.170.101:10006

  slots: (0 slots) slave

  replicates 9c6a98926b23585e2eeb49ae17cc77521041d3ed

S: 58b7b25501fdba04aef9b8cb47edef89092f10a7 192.168.170.101:10004

  slots: (0 slots) slave

  replicates b30fdabd07a4bef611c160828965b91a1cdd462a

[OK] All nodes agree about slots configuration.

>>> Check for open slots…

>>> Check slots coverage…

[OK] All 16384 slots covered.

[root@lab001 redis]# redis-trib.rb info 192.168.170.101:10001

192.168.170.101:10001 (b30fdabd…) -> 33357 keys | 5461 slots | 1 slaves.

192.168.170.101:10007 (7c1a0acf…) -> 33283 keys | 5462 slots | 1 slaves.

192.168.170.101:10003 (9c6a9892…) -> 33360 keys | 5461 slots | 1 slaves.

[OK] 100000 keys in 3 masters.

6.10 keys per slot on average.

总结：

1. slots 迁移在日常工作中，通常用于节点迁移、扩展，也可以根据服务器本身的压力将 slots 迁移至性能较优的服务器

2. slots 迁移过程当中，不影响数据的读写，这点已经做过实际的测试。

3. 迁移过程当中，应用配置应当至少包含一个集群 master 节点信息，否则有可能会造成数据访问异常的情况。迁移完成并配置同步更新至最新后，方可删除旧的空 slots 节点。

本文永久更新链接地址：http://www.linuxidc.com/Linux/2017-02/141083.htm