一、實驗環境
1、系統版本： Centos 7.6 x86_64 2、Redis版本 4.0.9 3、集羣IP信息 172.16.100.201 172.16.100.202 172.16.100.203 4、準備加入集羣的IP信息 172.16.100.204 172.16.100.205 172.16.100.206 5、目的 將Redis集羣的3主3從，擴容爲6主6從，204、205、206 三個新節點各新增1主1從！
二、安裝配置Redis集羣
1、在3臺服務器上安裝redis，每臺2個實例，如下： 172.16.100.201 8000 8001 172.16.100.202 8002 8003 172.16.100.203 8004 8005 開始安裝 #tar xf redis-4.0.9.tar.gz #cd redis-4.0.9 #make #mv redis-4.0.9 /opt/app/redis8000 2、提供配置文件 #cat /opt/app/redis8000/redis.conf daemonize yes port 8000 bind 172.16.100.201 appendonly no save 900 1 save 300 10 save 60 10000000 dir /opt/app/redis8000/db/ pidfile /opt/app/redis8000/redis_8000.pid logfile /opt/app/redis8000/logs/redis8000.log cluster-enabled yes cluster-config-file nodes8000.conf cluster-node-timeout 20000 cluster-require-full-coverage no 3、修改系統參數 #vim /etc/security/limits.conf * soft nofile 65535 * hard nofile 65535 * soft nproc 65535 * hard nproc 65535 #vim /etc/sysctl.conf #redis vm.overcommit_memory=1 net.core.somaxconn = 511 關閉大頁面 #echo never > /sys/kernel/mm/transparent_hugepage/enabled 使配置生效 #sysctl -p 啓動： /opt/app/redis8000/src/redis-server /opt/app/redis8000/redis.conf 以上是201服務器8000節點配置的例子，202和203服務器2個節點配置，參考上面即可，注意監聽ip地址和端口、路徑名稱需要作出相應的修改。
三、創建Redis 4.0.9 集羣（在201服務器操作即可）
1、安裝軟件包 #yum install ruby rubygems -y #gem install redis -v 3.3.5 2、創建集羣 #/opt/app/redis8000/src/redis-trib.rb create --replicas 1 172.16.100.201:8000 172.16.100.201:8001 172.16.100.202:8002 172.16.100.202:8003 172.16.100.203:8004 172.16.100.203:8005 3、查看集羣IP信息 172.16.100.203:8005 slave 172.16.100.201:8001 slave 172.16.100.203:8004 master 10923-16383 172.16.100.202:8003 slave 172.16.100.201:8000 master 0-5460 172.16.100.202:8002 master 5461-10922 將線上對應3主3從Redis集羣slot的dump.rdb拷貝到對應節點，並啓動，目的是讓實驗環境Redis集羣有數據，或者自己造一些數據，此步驟省略！爲了演示效果，我 這裏手動set幾個key，如下： 172.16.100.201:8000> set name1 jodan ………… 172.16.100.201:8000> set name10 kawayi …………
四、將新節點加入集羣並遷移slot(在172.16.100.201服務器操作)
注:在204、205、206各啓動2個redis實例，端口如下分配： 204 master 8006 slave 8007 205 master 8008 slave 8009 206 master 8010 slave 8011 1、配置啓動新服務器Redis(一共3臺服務器6個redis實例)，配置方法參考步驟二，這裏不再贅述。 2、將3個master節點加入集羣 原集羣詳細信息： 3主3從 # /opt/app/redis8000/src/redis-cli -h 172.16.100.201 -p 8000 cluster nodes 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 172.16.100.202:8002@18002 master - 0 1575702279000 3 connected 5461-10922 b87a9f751b1eb4496c2eff495d216c88c22065ac 172.16.100.203:8004@18004 master - 0 1575702277798 5 connected 10923-16383 95ccd1953fa78a1ffa599d65b72d547f8277c3b5 172.16.100.201:8001@18001 slave b87a9f751b1eb4496c2eff495d216c88c22065ac 0 1575702279804 5 connected 2c67f0832908ae6375fec57b2399a0a8f4c9e9cc 172.16.100.203:8005@18005 slave 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 0 1575702279000 6 connected 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 172.16.100.201:8000@18000 myself,master - 0 1575702278000 1 connected 0-5460 187eba647c002ff47674c71225c428fb8db59444 172.16.100.202:8003@18003 slave 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 0 1575702276795 4 connected 將172.16.100.204:8006 加入集羣， /opt/app/redis8000/src/redis-trib.rb add-node 172.16.100.204:8006 172.16.100.201:8000 將172.16.100.205:8008 加入集羣 /opt/app/redis8000/src/redis-trib.rb add-node 172.16.100.205:8008 172.16.100.201:8000 將172.16.100.206:8010 加入集羣 /opt/app/redis8000/src/redis-trib.rb add-node 172.16.100.206:8010 172.16.100.201:8000 查看加入3個master節點之後的集羣信息： #/opt/app/redis8000/src/redis-cli -h 172.16.100.201 -p 8000 cluster nodes 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 172.16.100.202:8002@18002 master - 0 1575704459051 3 connected 5461-10922 95ccd1953fa78a1ffa599d65b72d547f8277c3b5 172.16.100.201:8001@18001 slave b87a9f751b1eb4496c2eff495d216c88c22065ac 0 1575704457045 5 connected 187eba647c002ff47674c71225c428fb8db59444 172.16.100.202:8003@18003 slave 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 0 1575704457000 4 connected 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 172.16.100.201:8000@18000 myself,master - 0 1575704458000 1 connected 0-5460 c4772e933405eda022b0f7b837a67f05690c76da 172.16.100.204:8006@18006 master - 0 1575704458048 0 connected 564d7877350b0a4789f18162c393a04584f9d311 172.16.100.205:8008@18008 master - 0 1575704455000 7 connected b87a9f751b1eb4496c2eff495d216c88c22065ac 172.16.100.203:8004@18004 master - 0 1575704455040 5 connected 10923-16383 3dc917e0d7a1387caf646add2d06814cdb3560ab 172.16.100.206:8010@18010 master - 0 1575704458548 0 connected 2c67f0832908ae6375fec57b2399a0a8f4c9e9cc 172.16.100.203:8005@18005 slave 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 0 1575704457000 6 connected 可以看到新加入集羣的節點是沒有slot的，所以下面就需要將其他3個master節點的部分slot遷移過去。 3、開始slot自動遷移 #ruby /opt/app/redis8000/src/redis-trib.rb rebalance --auto-weights --use-empty-masters 172.16.100.201:8000 >>> Performing Cluster Check (using node 172.16.100.201:8000) [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Rebalancing across 6 nodes. Total weight = 6 Moving 2732 slots from 172.16.100.202:8002 to 172.16.100.204:8006 ################# 花費時間長短根據遷移數據量大小 Moving 2731 slots from 172.16.100.203:8004 to 172.16.100.206:8010 ################# Moving 2731 slots from 172.16.100.201:8000 to 172.16.100.205:8008 ################# 結束之後，再次查看集羣信息： # /opt/app/redis8000/src/redis-cli -h 172.16.100.201 -p 8000 cluster nodes 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 172.16.100.202:8002@18002 master - 0 1575706557000 3 connected 8193-10922 95ccd1953fa78a1ffa599d65b72d547f8277c3b5 172.16.100.201:8001@18001 slave b87a9f751b1eb4496c2eff495d216c88c22065ac 0 1575706557000 5 connected 187eba647c002ff47674c71225c428fb8db59444 172.16.100.202:8003@18003 slave 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 0 1575706554000 4 connected 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 172.16.100.201:8000@18000 myself,master - 0 1575706555000 1 connected 2731-5460 c4772e933405eda022b0f7b837a67f05690c76da 172.16.100.204:8006@18006 master - 0 1575706558000 9 connected 5461-8192 564d7877350b0a4789f18162c393a04584f9d311 172.16.100.205:8008@18008 master - 0 1575706557237 11 connected 0-2730 b87a9f751b1eb4496c2eff495d216c88c22065ac 172.16.100.203:8004@18004 master - 0 1575706556000 5 connected 13654-16383 3dc917e0d7a1387caf646add2d06814cdb3560ab 172.16.100.206:8010@18010 master - 0 1575706559243 10 connected 10923-13653 2c67f0832908ae6375fec57b2399a0a8f4c9e9cc 172.16.100.203:8005@18005 slave 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 0 1575706558240 6 connected 可以看出新加入集羣的3個master節點已經有slot了。 查看前面手動加的key是否成功遷移到了新master節點，如下： 172.16.100.201:8000> get name1 -> Redirected to slot [12933] located at 172.16.100.206:8010 #新節點 "jodan" 172.16.100.206:8010> get name2 -> Redirected to slot [742] located at 172.16.100.205:8008 #新節點 "kobe" 172.16.100.205:8008> get name3 -> Redirected to slot [4807] located at 172.16.100.201:8000 "onier" 172.16.100.201:8000> get name4 -> Redirected to slot [8736] located at 172.16.100.202:8002 "curry" 172.16.100.202:8002> get name5 -> Redirected to slot [12801] located at 172.16.100.206:8010 #新節點 "james" 172.16.100.206:8010> get name6 -> Redirected to slot [610] located at 172.16.100.205:8008 #新節點 "durant" 172.16.100.205:8008> get name7 -> Redirected to slot [4675] located at 172.16.100.201:8000 "timu" 172.16.100.201:8000> get name8 -> Redirected to slot [9132] located at 172.16.100.202:8002 "park" 172.16.100.202:8002> get name9 -> Redirected to slot [13197] located at 172.16.100.206:8010 #新節點 "qiaozhi" 可以看到有幾個key已經成功遷移到了新節點205和206！ 4、爲新master節點添加slave節點(在172.16.100.201節點操作) 爲了避免單點故障，設計主從如下： 204 205 206 8006 M1 8008 M2 8010 M3 8007 S3 8009 S1 8011 S2 將205@8009這個節點加爲 204@8006 的從節點 /opt/app/redis8000/src/redis-trib.rb add-node --slave --master-id c4772e933405eda022b0f7b837a67f05690c76da 172.16.100.205:8009 172.16.100.204:8006 將206@8011這個節點加爲 205@8008 的從節點 /opt/app/redis8000/src/redis-trib.rb add-node --slave --master-id 564d7877350b0a4789f18162c393a04584f9d311 172.16.100.206:8011 172.16.100.205:8008 將204@8007這個節點加爲 206@8010 的從節點 /opt/app/redis8000/src/redis-trib.rb add-node --slave --master-id 3dc917e0d7a1387caf646add2d06814cdb3560ab 172.16.100.204:8007 172.16.100.206:8010 再次查看集羣信息如下： #/opt/app/redis8000/src/redis-cli -h 172.16.100.201 -p 8000 cluster nodes 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 172.16.100.202:8002@18002 master - 0 1575708808057 3 connected 8193-10922 1d7c87447dd419ac7a2260dce726af03e7965c1a 172.16.100.204:8007@18007 slave 3dc917e0d7a1387caf646add2d06814cdb3560ab 0 1575708799027 10 connected 95ccd1953fa78a1ffa599d65b72d547f8277c3b5 172.16.100.201:8001@18001 slave b87a9f751b1eb4496c2eff495d216c88c22065ac 0 1575708807000 5 connected 187eba647c002ff47674c71225c428fb8db59444 172.16.100.202:8003@18003 slave 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 0 1575708806049 4 connected 9a02a2120d4a0f9bd8b3ae7e11ffe28d0e03d6fc 172.16.100.201:8000@18000 myself,master - 0 1575708806000 1 connected 2731-5460 c4772e933405eda022b0f7b837a67f05690c76da 172.16.100.204:8006@18006 master - 0 1575708803000 9 connected 5461-8192 564d7877350b0a4789f18162c393a04584f9d311 172.16.100.205:8008@18008 master - 0 1575708801000 11 connected 0-2730 735012e7c6f181f7e8a197fc1667ff7bc075361d 172.16.100.206:8011@18011 slave 564d7877350b0a4789f18162c393a04584f9d311 0 1575708807054 11 connected b87a9f751b1eb4496c2eff495d216c88c22065ac 172.16.100.203:8004@18004 master - 0 1575708805047 5 connected 13654-16383 5ba06662b9b260ca2cadcf2f7692e5e0e1a91474 172.16.100.205:8009@18009 slave c4772e933405eda022b0f7b837a67f05690c76da 0 1575708804045 9 connected 3dc917e0d7a1387caf646add2d06814cdb3560ab 172.16.100.206:8010@18010 master - 0 1575708805000 10 connected 10923-13653 2c67f0832908ae6375fec57b2399a0a8f4c9e9cc 172.16.100.203:8005@18005 slave 11ae0bcc3aeae0cb7e40c28f407e3d2a30504989 0 1575708806000 6 connected 遷移結束！！！
不足之處，請多多交流指出。