redis cluster的簡單學習筆記

 redis cluster

（1）自動将資料進行分片，每個master上放一部分資料

（2）提供内置的高可用支援，部分master不可用時，還是可以繼續工作的

redis cluster不用一緻性hash,而是使用hash slots來替代。

為了實作效果：實作了讀寫分離(master-slave)，高可用(redis-cluster本身的特性)，多個master協同(水準擴容)。做如下試驗：

在三台虛拟機上啟動6個redis執行個體，3個為master，3個為slave

1）,編寫配置檔案

redis cluster叢集，要求至少3個master，去組成一個高可用，健壯的分布式的叢集，每個master都建議至少給一個slave，

3個master，3個slave

3台虛拟機去搭建6個redis執行個體的redis cluster

不同虛拟機上建立目錄，比如在虛拟機A上：

mkdir -p /etc/redis-cluster

mkdir -p /var/log/redis

mkdir -p /var/redis/7001

mkdir -p /var/redis/7002

每台虛拟機上都需要将配置檔案修改一下選項，比如在虛拟機A上：

port 7001

cluster-enabled yes

cluster-config-file /etc/redis-cluster/node-7001.conf

cluster-node-timeout 15000

daemonize    yes                            

pidfile        /var/run/redis_7001.pid                         

dir         /var/redis/7001        

logfile /var/log/redis/7001.log

bind 192.168.0.101   

appendonly yes

将上面的配置檔案，在/etc/redis下放6個，

分别為: 7001.conf，7002.conf，7003.conf，7004.conf，7005.conf，7006.conf

2）,準備生産環境的啟動腳本

在/etc/init.d下，放6個啟動腳本，分别為:

 redis_7001, redis_7002, redis_7003, redis_7004, redis_7005, redis_7006。每個啟動腳本内，都修改對應的端口号

3）,分别在3台機器上，啟動6個redis執行個體。redis-trib.rb是Redis Cluster的一個常用工具。使用redis-trib.rb需要ruby環境，下面就是安裝ruby等環境

wget https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.1.tar.gz

tar -zxvf ruby-2.3.1.tar.gz

./configure -prefix=/usr/local/ruby

make && make install

cd ruby所在目錄

cp "ruby所在目錄"/bin/ruby /usr/bin

cp "ruby所在目錄"/bin/gem /usr/bin

wget http://rubygems.org/downloads/redis-3.3.0.gem

gem install -l ./redis-3.3.0.gem

gem list check redis gem

cp “redis安裝所在目錄”/src/redis-trib.rb /usr/bin

--replicas: 每個master有幾個slave

使用redis-tri.rb指令，

redis-trib.rb create --replicas 1 192.168.0.101:7001 192.168.0.101:7002 192.168.0.102:7003 192.168.0.102:7004 192.168.0.103:7005 192.168.0.103:7006

得到的結果如下：

>>> Creating cluster

>>> Performing hash slots allocation on 6 nodes...

Using 3 masters:

192.168.0.101:7001

192.168.0.102:7003

192.168.0.103:7005

Adding replica 192.168.0.102:7004 to 192.168.0.101:7001

Adding replica 192.168.0.101:7002 to 192.168.0.102:7003

Adding replica 192.168.0.103:7006 to 192.168.0.103:7005

M: 20df2234e622fcadcce1d135e7458dcfd1c16ca2 192.168.0.101:7001

   slots:0-5460 (5461 slots) master

S: 5ac6d025af59500553df2ba13a265d9519f8865a 192.168.0.101:7002

   replicates 01d1bbd83ec5ec1586d831cfc0edbd0d2ac58b3f

M: 01d1bbd83ec5ec1586d831cfc0edbd0d2ac58b3f 192.168.0.102:7003

   slots:5461-10922 (5462 slots) master

S: ec8d3bd658982ba4180df00fc5ae0d2b79b2fe5b 192.168.0.102:7004

   replicates 20df2234e622fcadcce1d135e7458dcfd1c16ca2

M: cf13c8086fcba76bb9b97a6bf0699069da419e1d 192.168.0.103:7005

   slots:10923-16383 (5461 slots) master

S: 05e3e313c07b31a136bd50191324ba52f90c58a7 192.168.0.103:7006

   replicates cf13c8086fcba76bb9b97a6bf0699069da419e1d

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 192.168.0.101:7001)

M: 20df2234e622fcadcce1d135e7458dcfd1c16ca2 192.168.0.101:7001

   slots:0-5460 (5461 slots) master

   1 additional replica(s)

S: 5ac6d025af59500553df2ba13a265d9519f8865a 192.168.0.101:7002

   slots: (0 slots) slave

   replicates 01d1bbd83ec5ec1586d831cfc0edbd0d2ac58b3f

S: 05e3e313c07b31a136bd50191324ba52f90c58a7 192.168.0.103:7006

   slots: (0 slots) slave

   replicates cf13c8086fcba76bb9b97a6bf0699069da419e1d

M: 01d1bbd83ec5ec1586d831cfc0edbd0d2ac58b3f 192.168.0.102:7003

   slots:5461-10922 (5462 slots) master

   1 additional replica(s)

M: cf13c8086fcba76bb9b97a6bf0699069da419e1d 192.168.0.103:7005

   slots:10923-16383 (5461 slots) master

   1 additional replica(s)

S: ec8d3bd658982ba4180df00fc5ae0d2b79b2fe5b 192.168.0.102:7004

   slots: (0 slots) slave

   replicates 20df2234e622fcadcce1d135e7458dcfd1c16ca2

[OK] All nodes agree about slots configuration.

>>> Check for open slots...

>>> Check slots coverage...

[OK] All 16384 slots covered.

從結果看得出，每個master虛拟機大概平均被配置設定了5461個slots

嘗試 check 一下，輸入：

redis-trib.rb check 192.168.0.101:7001

>>> Performing Cluster Check (using node 192.168.0.101:7001)

M: 20df2234e622fcadcce1d135e7458dcfd1c16ca2 192.168.0.101:7001

   slots:0-5460 (5461 slots) master

   1 additional replica(s)

S: 5ac6d025af59500553df2ba13a265d9519f8865a 192.168.0.101:7002

   slots: (0 slots) slave

   replicates 01d1bbd83ec5ec1586d831cfc0edbd0d2ac58b3f

S: 05e3e313c07b31a136bd50191324ba52f90c58a7 192.168.0.103:7006

   slots: (0 slots) slave

   replicates cf13c8086fcba76bb9b97a6bf0699069da419e1d

M: 01d1bbd83ec5ec1586d831cfc0edbd0d2ac58b3f 192.168.0.102:7003

   slots:5461-10922 (5462 slots) master

   1 additional replica(s)

M: cf13c8086fcba76bb9b97a6bf0699069da419e1d 192.168.0.103:7005

   slots:10923-16383 (5461 slots) master

   1 additional replica(s)

S: ec8d3bd658982ba4180df00fc5ae0d2b79b2fe5b 192.168.0.102:7004

   slots: (0 slots) slave

   replicates 20df2234e622fcadcce1d135e7458dcfd1c16ca2

[OK] All nodes agree about slots configuration.

>>> Check for open slots...

>>> Check slots coverage...

[OK] All 16384 slots covered.

沒問題，16384個slots全被配置設定了。