Redis 集羣管理常見操做

Redis 內置客戶端 redis-cli 經過 --cluster 選項集成了多個 Redis 集羣管理工具， 這些工具能夠執行建立集羣、向集羣中添加或移除節點、對集羣實施重分片以及負載均衡等操做， 它們每個都很是強大：

$ redis-cli --cluster help Cluster Manager Commands: create host1:port1 ... hostN:portN --cluster-replicas <arg> check host:port info host:port fix host:port reshard host:port --cluster-from <arg> --cluster-to <arg> --cluster-slots <arg> --cluster-yes --cluster-timeout <arg> --cluster-pipeline <arg> rebalance host:port --cluster-weight <node1=w1...nodeN=wN> --cluster-use-empty-masters --cluster-timeout <arg> --cluster-simulate --cluster-pipeline <arg> --cluster-threshold <arg> add-node new_host:new_port existing_host:existing_port --cluster-slave --cluster-master-id <arg> del-node host:port node_id call host:port command arg arg .. arg set-timeout host:port milliseconds import host:port --cluster-from <arg> --cluster-copy --cluster-replace help For check, fix, reshard, del-node, set-timeout you can specify the host and port of any working node in the cluster.

本文將對上述工具的其中一些進行介紹， 幫助你們初步地瞭解這些工具的基本用法。

建立集羣的工做能夠經過 create 命令來完成， 用戶只須要給定各個節點的地址以及想要設置的從服務器數量便可。 好比說， 經過執行如下命令， 咱們能夠建立出一個由三個主節點和三個從節點組成的集羣：

$ redis-cli --cluster create 127.0.0.1:30001 127.0.0.1:30002 127.0.0.1:30003 127.0.0.1:30004 127.0.0.1:30005 127.0.0.1:30006 --cluster-replicas 1 >>> Performing hash slots allocation on 6 nodes... Master[0] -> Slots 0 - 5460 Master[1] -> Slots 5461 - 10922 Master[2] -> Slots 10923 - 16383 Adding replica 127.0.0.1:30004 to 127.0.0.1:30001 Adding replica 127.0.0.1:30005 to 127.0.0.1:30002 Adding replica 127.0.0.1:30006 to 127.0.0.1:30003 >>> Trying to optimize slaves allocation for anti-affinity [WARNING] Some slaves are in the same host as their master M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001 slots:[0-5460] (5461 slots) master M: 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 127.0.0.1:30002 slots:[5461-10922] (5462 slots) master M: 07e230805903e4e1657743a2e4d8811a59e2f32f 127.0.0.1:30003 slots:[10923-16383] (5461 slots) master S: 4788fd4d92387fc5d38a2cd12f0c0d80fc0f6609 127.0.0.1:30004 replicates 4979f8583676c46039672fb7319e917e4b303707 S: b45a7f4355ea733a3177b89654c10f9c31092e92 127.0.0.1:30005 replicates 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 S: 7c56ffba63e3758bc4c2e9b6a55caf294bb21650 127.0.0.1:30006 replicates 07e230805903e4e1657743a2e4d8811a59e2f32f 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 127.0.0.1:30001) M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001 slots:[0-5460] (5461 slots) master 1 additional replica(s) S: 4788fd4d92387fc5d38a2cd12f0c0d80fc0f6609 127.0.0.1:30004 slots: (0 slots) slave replicates 4979f8583676c46039672fb7319e917e4b303707 S: b45a7f4355ea733a3177b89654c10f9c31092e92 127.0.0.1:30005 slots: (0 slots) slave replicates 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 S: 7c56ffba63e3758bc4c2e9b6a55caf294bb21650 127.0.0.1:30006 slots: (0 slots) slave replicates 07e230805903e4e1657743a2e4d8811a59e2f32f M: 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 127.0.0.1:30002 slots:[5461-10922] (5462 slots) master 1 additional replica(s) M: 07e230805903e4e1657743a2e4d8811a59e2f32f 127.0.0.1:30003 slots:[10923-16383] (5461 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.

經過執行 info 命令， 用戶能夠看到集羣包含的主從節點數量， 以及集羣中的鍵、槽分佈信息：

$ redis-cli --cluster info 127.0.0.1:30001 127.0.0.1:30001 (4979f858...) -> 1 keys | 5461 slots | 1 slaves. 127.0.0.1:30002 (4ff303d9...) -> 4 keys | 5462 slots | 1 slaves. 127.0.0.1:30003 (07e23080...) -> 3 keys | 5461 slots | 1 slaves. [OK] 8 keys in 3 masters. 0.00 keys per slot on average.

添加節點/移除節點 在擁有了集羣以後， 用戶就能夠經過執行 add-node 命令或者 del-node 命令， 向集羣裏面添加新節點又或者移除已有的節點。 好比說， 經過執行如下命令， 咱們能夠把節點 30007 添加至集羣當中：

redis-cli --cluster add-node 127.0.0.1:30007 127.0.0.1:30001 >>> Adding node 127.0.0.1:30007 to cluster 127.0.0.1:30001 >>> Performing Cluster Check (using node 127.0.0.1:30001) ... [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Send CLUSTER MEET to node 127.0.0.1:30007 to make it join the cluster. [OK] New node added correctly.

又或者經過執行如下命令， 將 ID 爲 e1971e... 的節點 30007 移出集羣：

redis-cli --cluster del-node 127.0.0.1:30001 e1971eef02709cf4698a6fcb09935a910982ab3b >>> Removing node e1971eef02709cf4698a6fcb09935a910982ab3b from cluster 127.0.0.1:30001 >>> Sending CLUSTER FORGET messages to the cluster... >>> SHUTDOWN the node.

經過執行 reshard 命令， 用戶能夠將指定數量的槽從一個節點遷移至另外一個節點。 好比說， 經過執行如下命令， 咱們能夠將 ID 爲 4979f... 的節點 30001 目前負責的其中 10 個槽轉交給 ID 爲 1cd87d... 的節點 30007 負責：

$ redis-cli --cluster reshard 127.0.0.1:30001 --cluster-from 4979f8583676c46039672fb7319e917e4b303707 --cluster-to 1cd87d132101893b7aa2b81cf333b2f7be9e1b75 --cluster-slots 10 >>> Performing Cluster Check (using node 127.0.0.1:30001) M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001 slots:[0-5460] (5461 slots) master 1 additional replica(s) S: 4788fd4d92387fc5d38a2cd12f0c0d80fc0f6609 127.0.0.1:30004 slots: (0 slots) slave replicates 4979f8583676c46039672fb7319e917e4b303707 S: b45a7f4355ea733a3177b89654c10f9c31092e92 127.0.0.1:30005 slots: (0 slots) slave replicates 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 M: 1cd87d132101893b7aa2b81cf333b2f7be9e1b75 127.0.0.1:30007 slots: (0 slots) master S: 7c56ffba63e3758bc4c2e9b6a55caf294bb21650 127.0.0.1:30006 slots: (0 slots) slave replicates 07e230805903e4e1657743a2e4d8811a59e2f32f M: 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 127.0.0.1:30002 slots:[5461-10922] (5462 slots) master 1 additional replica(s) M: 07e230805903e4e1657743a2e4d8811a59e2f32f 127.0.0.1:30003 slots:[10923-16383] (5461 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. Ready to move 10 slots. Source nodes: M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001 slots:[0-5460] (5461 slots) master 1 additional replica(s) Destination node: M: 1cd87d132101893b7aa2b81cf333b2f7be9e1b75 127.0.0.1:30007 slots: (0 slots) master Resharding plan: Moving slot 0 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 1 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 2 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 3 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 4 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 5 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 6 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 7 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 8 from 4979f8583676c46039672fb7319e917e4b303707 Moving slot 9 from 4979f8583676c46039672fb7319e917e4b303707 Do you want to proceed with the proposed reshard plan (yes/no)? yes Moving slot 0 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 1 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 2 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 3 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 4 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 5 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 6 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 7 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 8 from 127.0.0.1:30001 to 127.0.0.1:30007: Moving slot 9 from 127.0.0.1:30001 to 127.0.0.1:30007:

當集羣中各個節點的槽配置趨於不均衡的時候， 各個節點負擔的載荷就可能會出現區別， 並致使某些節點超負荷運行， 而某些節點則長時間空置。 爲了解決這個問題， 用戶能夠經過執行 rebalance 命令， 讓各個節點負責的槽數量從新回到平均狀態。 好比說， 對於如下這個由三個節點組成， 而且三個節點分別負責 2000 、 11384 和 3000 個槽的集羣來講：

$ redis-cli --cluster info 127.0.0.1:30001 127.0.0.1:30001 (61d1f17b...) -> 0 keys | 2000 slots | 1 slaves. 127.0.0.1:30002 (101fbae9...) -> 0 keys | 11384 slots | 1 slaves. 127.0.0.1:30003 (31822e0a...) -> 0 keys | 3000 slots | 1 slaves. [OK] 0 keys in 3 masters. 0.00 keys per slot on average.

咱們能夠經過執行如下命令來從新分配各個節點負責的槽：

$ redis-cli --cluster rebalance 127.0.0.1:30001 >>> Performing Cluster Check (using node 127.0.0.1:30001) [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Rebalancing across 3 nodes. Total weight = 3.00 Moving 3462 slots from 127.0.0.1:30002 to 127.0.0.1:30001 #####...##### Moving 2461 slots from 127.0.0.1:30002 to 127.0.0.1:30003 #####...#####

在複雜均衡操做執行完畢以後， 集羣各個節點負責的槽數量將趨於平均， 這樣它們各自負擔的載荷也會從新回到平均狀態：

$ redis-cli --cluster info 127.0.0.1:30001 127.0.0.1:30001 (61d1f17b...) -> 0 keys | 5462 slots | 1 slaves. 127.0.0.1:30002 (101fbae9...) -> 0 keys | 5461 slots | 1 slaves. 127.0.0.1:30003 (31822e0a...) -> 0 keys | 5461 slots | 1 slaves. [OK] 0 keys in 3 masters. 0.00 keys per slot on average.

在集羣的全部節點中執行命令 若是用戶想要對集羣中的全部節點執行同一個命令， 那麼能夠經過 call 命令來完成。 好比說， 經過執行如下命令， 用戶就可讓集羣中的每一個節點都執行 DBSIZE 命令， 從而獲得各個節點各自的數據庫大小：

$ redis-cli --cluster call 127.0.0.1:30001 DBSIZE >>> Calling DBSIZE 127.0.0.1:30001: (integer) 0 127.0.0.1:30004: (integer) 0 127.0.0.1:30005: (integer) 3 127.0.0.1:30006: (integer) 0 127.0.0.1:30002: (integer) 3 127.0.0.1:30003: (integer) 0

好的， 關於 redis-cli --cluster 選項的簡單介紹就到此結束了， 但願這些介紹能夠幫助你們更好地瞭解到這些命令。 你們有興趣的話， 也能夠以此爲起點， 更加深刻地學習這些命令。

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