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由于之前的redis cluster物理硬件性能不足。决定升级到更好的服务器上。
考虑到redis是核心生产数据库，决定在线迁移，迁移过程，不中断服务。
下面是测试环境的完成迁移步骤：
1. 原环境（测试环境，没有创建slave）
2. 在新主机上，启动三个redis实例
10.21.10.120:7000 10.21.10.120:7001 10.21.10.120:70023. 将三个redis，都添加到集群中. 命令格式redis-trib.rb add-node <新增节点名> < 原集群节点名>
./redis-trib.rb add-node 10.21.10.120:7000 10.21.14.251:7000 ./redis-trib.rb add-node 10.21.10.120:7001 10.21.14.251:7000 ./redis-trib.rb add-node 10.21.10.120:7002 10.21.14.251:70004. 确认添加成功之后，开始reshard slot
./redis-trib.rb reshard 10.21.10.120:70005. 遇到点问题，由于网络超时等原因，导致resharding中断。然后出现两边都有slot的情况，需要通过fix的方式来修复
[redis@ip-10-21-14-251 redis]$ ./redis-trib.rb reshard 10.21.10.120:7000 >>> Performing Cluster Check (using node 10.21.10.120:7000) M: 4422ab38377fa8828e0f7884570b3b482a66496b 10.21.10.120:7000 slots:5026-5460 (435 slots) master 0 additional replica(s) M: 5b38e63a1091baa3a871a52275489a2aa1d28bfb 10.21.10.120:7002 slots:894-3397 (2504 slots) master 0 additional replica(s) M: bb1572074d41254e5b4d5aae5c52e54f5129d6d5 10.21.14.251:7001 slots:3398-4999,5461-15922 (12064 slots) master 0 additional replica(s) M: 396a7fbd2ec61752f9e848a1d8cc7b405aef0356 10.21.14.251:7000 slots: (0 slots) master 0 additional replica(s) M: 9f215e7e4b511f3d2bbf5d734731899b71a62a3b 10.21.10.120:7001 slots:0-893,5000-5025,15923-15948 (946 slots) master 0 additional replica(s) M: 0c9b383f65ae4fefc5e02617fb76a845d7510a53 10.21.14.251:7002 slots:15949-16383 (435 slots) master 0 additional replica(s) [OK] All nodes agree about slots configuration. >>> Check for open slots... [WARNING] Node 10.21.10.120:7002 has slots in importing state (3398). [WARNING] Node 10.21.14.251:7001 has slots in migrating state (3398). [WARNING] The following slots are open: 3398 >>> Check slots coverage... [OK] All 16384 slots covered. *** Please fix your cluster problems before resharding <<<<<<<<<<<<<<<<<<<<<6. 可以使用下面命令进行集群检查
./redis-trib.rb check 10.21.10.120:70007. 执行下面命令进行修复，然后就可以继续reshard slot了
./redis-trib.rb fix 10.21.10.120:70008. 全部slot迁移完成
$ ./redis-trib.rb check 10.21.10.120:7000 >>> Performing Cluster Check (using node 10.21.10.120:7000) M: 4422ab38377fa8828e0f7884570b3b482a66496b 10.21.10.120:7000 slots:3399-4999,5026-7332 (3908 slots) master 0 additional replica(s) M: 5b38e63a1091baa3a871a52275489a2aa1d28bfb 10.21.10.120:7002 slots:894-3398,7333-15332,15949-16383 (10940 slots) master 0 additional replica(s) M: bb1572074d41254e5b4d5aae5c52e54f5129d6d5 10.21.14.251:7001 slots: (0 slots) master 0 additional replica(s) M: 396a7fbd2ec61752f9e848a1d8cc7b405aef0356 10.21.14.251:7000 slots: (0 slots) master 0 additional replica(s) M: 9f215e7e4b511f3d2bbf5d734731899b71a62a3b 10.21.10.120:7001 slots:0-893,5000-5025,15333-15948 (1536 slots) master 0 additional replica(s) M: 0c9b383f65ae4fefc5e02617fb76a845d7510a53 10.21.14.251:7002 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.确认一下状态
[redis@ip-10-21-14-251 redis]$ ./redis-cli -p 7000 cluster nodes bb1572074d41254e5b4d5aae5c52e54f5129d6d5 10.21.14.251:7001 master - 0 1509611814919 6 connected 9f215e7e4b511f3d2bbf5d734731899b71a62a3b 10.21.10.120:7001 master - 0 1509611811917 14 connected 0-893 5000-5025 15333-15948 5b38e63a1091baa3a871a52275489a2aa1d28bfb 10.21.10.120:7002 master - 0 1509611815923 13 connected 894-3398 7333-15332 15949-16383 396a7fbd2ec61752f9e848a1d8cc7b405aef0356 10.21.14.251:7000 myself,master - 0 0 1 connected 4422ab38377fa8828e0f7884570b3b482a66496b 10.21.10.120:7000 master - 0 1509611813919 12 connected 3399-4999 5026-7332 0c9b383f65ae4fefc5e02617fb76a845d7510a53 10.21.14.251:7002 master - 0 1509611812917 3 connected9. 确认状态OK的话，开始删除节点
./redis-trib.rb del-node 10.21.14.251:7000 396a7fbd2ec61752f9e848a1d8cc7b405aef0356 ./redis-trib.rb del-node 10.21.14.251:7001 bb1572074d41254e5b4d5aae5c52e54f5129d6d5 ./redis-trib.rb del-node 10.21.14.251:7002 0c9b383f65ae4fefc5e02617fb76a845d7510a5310. 干掉10.21.14.251:7002成功,
[redis@ip-10-21-14-251 redis]$ ./redis-trib.rb del-node 10.21.14.251:7002 0c9b383f65ae4fefc5e02617fb76a845d7510a53 >>> Removing node 0c9b383f65ae4fefc5e02617fb76a845d7510a53 from cluster 10.21.14.251:7002 >>> Sending CLUSTER FORGET messages to the cluster... >>> SHUTDOWN the node. [envuser@ip-10-21-14-251 redis]$ ./redis-trib.rb check 10.21.10.120:7000 >>> Performing Cluster Check (using node 10.21.10.120:7000) M: 4422ab38377fa8828e0f7884570b3b482a66496b 10.21.10.120:7000 slots:3399-4999,5026-7332 (3908 slots) master 0 additional replica(s) M: 5b38e63a1091baa3a871a52275489a2aa1d28bfb 10.21.10.120:7002 slots:894-3398,7333-15332,15949-16383 (10940 slots) master 0 additional replica(s) M: bb1572074d41254e5b4d5aae5c52e54f5129d6d5 10.21.14.251:7001 slots: (0 slots) master 0 additional replica(s) M: 396a7fbd2ec61752f9e848a1d8cc7b405aef0356 10.21.14.251:7000 slots: (0 slots) master 0 additional replica(s) M: 9f215e7e4b511f3d2bbf5d734731899b71a62a3b 10.21.10.120:7001 slots:0-893,5000-5025,15333-15948 (1536 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.状态检查
[redis@ip-10-21-14-251 redis]$ ./redis-cli -p 7000 cluster nodes bb1572074d41254e5b4d5aae5c52e54f5129d6d5 10.21.14.251:7001 master - 0 1509611900094 6 connected 9f215e7e4b511f3d2bbf5d734731899b71a62a3b 10.21.10.120:7001 master - 0 1509611902100 14 connected 0-893 5000-5025 15333-15948 5b38e63a1091baa3a871a52275489a2aa1d28bfb 10.21.10.120:7002 master - 0 1509611901098 13 connected 894-3398 7333-15332 15949-16383 396a7fbd2ec61752f9e848a1d8cc7b405aef0356 10.21.14.251:7000 myself,master - 0 0 1 connected 4422ab38377fa8828e0f7884570b3b482a66496b 10.21.10.120:7000 master - 0 1509611899093 12 connected 3399-4999 5026-7332根据上面步骤，删除剩余节点即可。
经过测试，应用在迁移过程中，没有受到任何影响。但是应用连接池的IP需要找机会增加10.21.10.120。
更多链接，请参考：
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