概述
Redis 分片集群旨在应对业务增长带来的数据增长， 实现在线动态横向扩缩容，处理集群中每个主节点 16384 哈希槽的子集； 高可用性部署也可以稳定， 一个或多个副本节点即将启用每个分片节点； 当主节点挂断时，相应的副本节点自动升级为新主节点，当原主节点重新启动时，自动成为新主节点的副本节点； 当一对分片主从节点出现故障时，整个集群无法正常工作，需要人工干预恢复并启动故障节点
分片集群
1.创建一个 3 分片节点集群
# 创建具有 3 每个分片节点的集群，每个分片都有 1 个副本 # redis-cli --cluster create 192.168.31.17:6384 192.168.31.18:6384 192.168.31.19:6384 --cluster-replicas 1 # 创建具有 3 分片节点集群， 默认无副本 redis-cli --cluster create 192.168.31.17:6384 192.168.31.18:6384 192.168.31.19:6384 > >>> Performing hash slots allocation on 3 nodes... > Master[0] -> Slots 0 - 5460 > Master[1] -> Slots 5461 - 10922 > Master[2] -> Slots 10923 - 16383 > M: 1db08d1048b20b22dfbf5c5d724d95f46a843d29 192.168.31.17:6384 > slots:[0-5460] (5461 slots) master > M: 3f9d82efdf04bb5fcf3741de4ea9314925bbeefd 192.168.31.18:6384 > slots:[5461-10922] (5462 slots) master > M: 16a0c6947fcb7d498b7c96aa5b5a70491298e966 192.168.31.19:6384 > slots:[10923-16383] (5461 slots) master > 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 192.168.31.17:6384) > M: 1db08d1048b20b22dfbf5c5d724d95f46a843d29 192.168.31.17:6384 > slots:[0-5460] (5461 slots) master > M: 16a0c6947fcb7d498b7c96aa5b5a70491298e966 192.168.31.19:6384 > slots:[10923-16383] (5461 slots) master > M: 3f9d82efdf04bb5fcf3741de4ea9314925bbeefd 192.168.31.18:6384 > slots:[5461-10922] (5462 slots) master > [OK] All nodes agree about slots configuration. > >>> Check for open slots... > >>> Check slots coverage... > [OK] All 16384 slots covered.验证
1、查看指定 redis 节点状态(包括键、内存使用、请求、连接等)
redis-cli --stat -p 6384 -h 192.168.31.17 > ------- data ------ --------------------- load -------------------- - child - > keys mem clients blocked requests connections > 30022 9.25M 2 0 30518 ( 2) 59 > 30022 9.25M 2 0 30520 ( 2) 59 > 30022 9.25M 2 0 30522 ( 2) 59 > 30022 9.25M 2 0 30524 ( 2) 59 > 30022 9.25M 2 0 30526 ( 2) 59 > 30022 9.25M 2 0 30528 ( 2) 59 > 30022 9.25M 2 0 30530 ( 2) 59 2.检查主节点哈希槽和键的分布情况， 以及副本数和键总数 redis-cli --cluster info 192.168.31.17:6384 > 192.168.31.18:6384 (79c19006...) -> 49888 keys | 5462 slots | 1 slaves. > 192.168.31.17:6385 (3faafe60...) -> 50115 keys | 5461 slots | 1 slaves. > 192.168.31.19:6384 (df7d9f8e...) -> 49995 keys | 5461 slots | 1 slaves. > [OK] 149998 keys in 3 masters. > 9.16 keys per slot on average.集群管理
1、redis-cli 互动命令行
redis-cli -p 6384 -h 192.168.31.17 # 查看集群节点信息 cluster nodes # meet 添加节点, 执行任何节点 cluster meet 192.168.31.17 6385 # forget 根据节点 ID 删除节点, 该命令需要在所有节点执行 cluster forget 82d14741e161d07012783ae7c9bf1ef20ddc28a0 # 将当前 cluster 节点配置为指定主节点(1db08d1048b20b22dfbf5c5d724d95f46a843d29)副本节点 cluster replicate 1db08d1048b20b22dfbf5c5d724d95f46a843d29 # 查看指定 master 节点(1db08d1048b20b22dfbf5c5d724d95f46a843d29)副本节点 cluster replicas 1db08d1048b20b22dfbf5c5d724d95f46a843d29 cluster reset # 重置当前节点集群状态文件 nodes.conf2、redis-cli –cluster 子命令
# 在集群中所有节点上执行命令 client list redis-cli --cluster call 192.168.31.17:6384 client list # 将节点 192.168.31.17:6385 添加新的主节点， 需要从其他主节点迁移到新的主节点才能正常工作 redis-cli --cluster add-node 192.168.31.17:6385 192.168.31.17:6384 # 将节点 192.168.31.17:6385 添加为主节点(1)db08d1048b20b22dfbf5c5d724d95f46a843d29)的从节点 redis-cli --cluster add-node 192.168.31.17:6385 192.168.31.17:6384 --cluster-slave --cluster-master-id 1db08d1048b20b22dfbf5c5d724d95f46a843d29 # 删除节点 82d14741e161d07012783ae7c9bf1ef20ddc28a0 并关闭节点 redis-cli --cluster del-node 192.168.31.17:6384 82d14741e161d07012783ae7c9bf1ef20ddc28a0 # 从指定节点迁移 1024 槽位于目标节点 073ad3a6dfe64289be66c6d8e302b29afc4b0ec7 redis-cli --cluster reshard 192.168.31.17:6385 --cluster-from 1db08d1048b20b22dfbf5c5d724d95f46a843d29 --cluster-to 073ad3a6dfe64289be66c6d8e302b29afc4b0ec7 --cluster-slots 1024 # 使用以下命令， 进入交互式输入节点间相应参数值的槽位移 redis-cli --cluster reshard 192.168.31.17:6384 # 各节点槽位不平衡时，每个节点的槽位自动平衡 slots redis-cli --cluster rebalance 192.168.31.17:6384扩容
1.集群主节点扩容， 由 3 扩展到个主节点 5 个主节点
// 添加新节点 192.168.31.{18,19}:6386 redis-cli --cluster add-node 192.168.31.18:6386 192.168.31.17:6384 redis-cli --cluster add-node 192.168.31.19:6386 192.168.31.17:6384 // 哈希槽的自动平衡集群主节点分布 redis-ci --cluster rebalance 192.168.31.17:6384 --cluster-use-empty-masters
redis-cli --cluster info 192.168.31.17:6384
> 192.168.31.18:6386 (c64357f2...) -> 29894 keys | 3278 slots | 0 slaves.
> 192.168.31.18:6384 (79c19006...) -> 29927 keys | 3276 slots | 1 slaves.
> 192.168.31.17:6385 (3faafe60...) -> 29835 keys | 3276 slots | 1 slaves.
> 192.168.31.19:6384 (df7d9f8e...) -> 30083 keys | 3276 slots | 1 slaves.
> 192.168.31.19:6386 (a0f71de7...) -> 30259 keys | 3278 slots | 0 slaves.
> [OK] 149998 keys in 5 masters.
> 9.16 keys per slot on average.缩容
1、集群主节点扩容, 由 5 个主节点扩展到 3 个主节点
// 迁移节点 192.168.31.18:6386 的哈希槽
redis-cli --cluster reshard 192.168.31.17:6384 \
--cluster-from c64357f288902d1209fdf91f4804bf13b2a59fcf \
--cluster-to 79c19006ae3dcd12522090ddcc2b5b917b0feb2a \
--cluster-slots 3278 \
--cluster-yes
// 迁移节点 192.168.31.19:6386 的哈希槽
redis-cli --cluster reshard 192.168.31.17:6384 \
--cluster-from a0f71de78c2355f99de2b4c19796afb02e23c623 \
--cluster-to df7d9f8e2d7dbad37bdd1094c2770d1feabbd228 \
--cluster-slots 3278 \
--cluster-yes
// 查看各主节点哈希槽、键的分布情况
redis-cli --cluster info 192.168.31.17:6384
> 192.168.31.18:6386 (c64357f2...) -> 0 keys | 0 slots | 0 slaves.
> 192.168.31.18:6384 (79c19006...) -> 59821 keys | 6554 slots | 1 slaves.
> 192.168.31.17:6385 (3faafe60...) -> 29835 keys | 3276 slots | 1 slaves.
> 192.168.31.19:6384 (df7d9f8e...) -> 60342 keys | 6554 slots | 1 slaves.
> 192.168.31.19:6386 (a0f71de7...) -> 0 keys | 0 slots | 0 slaves.
> [OK] 149998 keys in 5 masters.
> 9.16 keys per slot on average.
// 自动平衡集群各主节点哈希槽的分布
redis-cli --cluster rebalance 192.168.31.17:6384
// 删除节点 192.168.31.{18,19}:6386
redis-cli --cluster del-node 192.168.31.17:6384 c64357f288902d1209fdf91f4804bf13b2a59fcf
redis-cli --cluster del-node 192.168.31.17:6384 a0f71de78c2355f99de2b4c19796afb02e23c623
// 查看各主节点哈希槽、键的分布情况
redis-cli --cluster info 192.168.31.17:6384
> 192.168.31.18:6384 (79c19006...) -> 49762 keys | 5461 slots | 1 slaves.
> 192.168.31.17:6385 (3faafe60...) -> 50060 keys | 5462 slots | 1 slaves.
> 192.168.31.19:6384 (df7d9f8e...) -> 50176 keys | 5461 slots | 1 slaves.
> [OK] 149998 keys in 3 masters.
> 9.16 keys per slot on average.迁移
Redis-shake 是一个用于在两个 Redis 之间同步数据的工具,支持 Redis Cluster 的在线迁移与离线迁移(备份文件导入) 支持解析、恢复、备份、同步四个功能
1、在线迁移
首次全量同步,然后进行增量的拉取(通过 psync 命令)
# 创建迁移目标 redis 集群
redis-cli --cluster create 192.168.31.17:6386 192.168.31.18:6386 192.168.31.19:6386
# cat redis-shake.conf 源及目标端主要配置项, 其它配置项默认即可
source.type: cluster
# master 可改为 slave, 表示从副本同步数据到目标端, 192.168.31.19 为任意源端 redis 节点
source.address: master@192.168.31.19:6384
target.type: cluster
target.address: master@192.168.31.19:6386./redis-shake -type sync -conf redis-shake.conf
2、离线迁移
适用于源实例与目标实例的网络无法连通的场景,或源端实例部署在其他云厂商 Redis 服务中,无法实现在线迁移
# cat redis-shake.conf 源及目标端主要配置项, 其它配置项默认即可
source.address: master@192.168.31.19:6384
# restore 导入数据时指定的备份文件
source.rdb.input: local_dump.0;local_dump.1;local_dump.2
target.type: cluster
target.address: master@192.168.31.19:6386备份: ./redis-shake -type dump -conf redis-shake.conf
恢复: ./redis-shake -type restore -conf redis-shake.conf
来源：Redis Cluster 部署、在线扩容、缩容、迁移、集群管理实践-武穆逸仙https://www.iwmyx.cn/redisclusterbszxa.html
来源：运维技术帮