1 cluster模式簡介
redis有Redis Sentinel、Redis Cluster兩種叢集方式，從redis3.0開始才支援Redis Cluster模式，常見部署方式為3主3從。3個從redis與三個主redis一一對應，叢集内置資料自動分片機制，叢集内部将所有的key經過hash後映射到16384個Slot中，叢集中的每個Redis Instance負責其中的一部分的Slot的讀寫。從下圖中可以看到資料叢集中的資料走向。
2 環境搭建
2.1 部署環境
由于環境有限，在同一台機器上搭建僞叢集，部署如下：
| master | slave |
| 192.168.8.16:7000 | 192.168.8.16:7003 |
| 192.168.8.16:7001 | 192.168.8.16:7004 |
| 192.168.8.16:7002 | 192.168.8.16:7005 |
2.2 redis 安裝：
# wget http://download.redis.io/releases/redis-3.2.6.tar.gz
# tar xzf redis-3.2.6.tar.gz
# cd redis-3.2.6
# make
# make isntall
2.3 配置并啟動redis
1、在redis-3.2.6目錄下建立cluster/7000、cluster/7001、cluster/7002、cluster/7003、cluster/7004、cluster/7005目錄
2、将redis-3.2.6目錄下的redis.conf拷貝到cluster/7000目錄下，配置做如下調整：
bind 192.168.8.16 127.0.0.1
port 7000
pidfile /var/run/redis_7000.pid
appendonly yes
cluster-enabled yes
cluster-config-file /root/home/redis-3.2.6/cluster/7000/nodes.conf
dir /root/home/redis-3.2.6/cluster/7000/
cluster-node-timeout 15000
3、cluster/7001、cluster/7002、cluster/7003、cluster/7004、cluster/7005目錄的redis.conf可以參考上面的方式做調整
4、分别啟動6個執行個體：./redis-server /root/home/redis-3.2.6/cluster/7000/redis.conf
cluster 相關參數說明：
1、cluster-enabled yes #開啟叢集
2、cluster-config-file nodes-6379.conf #叢集配置資訊檔案，由Redis自行更新，不用手動配置。每個節點都有一個叢集配置檔案用于持久化儲存叢集資訊，需確定與運作中執行個體的配置檔案名 不沖突。
3、cluster-node-timeout 15000 #節點互連逾時時間，毫秒為機關
4、cluster-slave-validity-factor 10 #在進行故障轉移的時候全部slave都會請求申請為master，但是有些slave可能與master斷開連接配接一段時間了導緻資料過于陳舊，不應該被提升為master。該參數就是用來判斷slave節點與master斷線的時間是否過長。判斷方法是：比較slave斷開連接配接的時間和(node-timeout * slave-validity-factor)+ repl-ping-slave-period如果節點逾時時間為三十秒, 并且slave-validity-factor為10，假設預設的repl-ping-slave-period是10秒，即如果超過310秒slave将不會嘗試進行故障轉移
5、cluster-migration-barrier 1 #master的slave數量大于該值，slave才能遷移到其他孤立master上，如這個參數被設為2，那麼隻有當一個主節點擁有2個可工作的從節點時，它的一個從節點才會嘗試遷移。
6、cluster-require-full-coverage yes #叢集全部的slot有節點負責，叢集狀态才為ok并提供服務。設定為no可以在slot沒有全部配置設定的時候提供服務。不建議打開該配置，這樣會造成分區的時候，小分區的master一直在接受寫請求，而造成很長時間資料不一緻。
7、Appendonly是一種能夠提供非常好的持久化的模式，例如使用預設的Fsync方案，Redis能在發生伺服器電源故障或作業系統仍然正常運作但Redis程序莫名挂掉的情況下，隻丢失1秒的資料
2.4 安裝ruby和rubygems
安裝ruby
[[email protected] local]# tar zxvf ruby-2.4.0.tar.gz
[[email protected] local]# cd ruby-2.4.0
[[email protected] local]#./configure && make && make install
[[email protected] local]# ruby --version
ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-linux]
安裝rubygems
[[email protected]]# tar zxvf rubygems-3.0.2.tgz
[[email protected] ]# cd rubygems-3.0.2
[[email protected] rubygems-3.0.2]# ruby setup.rb
[[email protected] rubygems-3.0.2]# gem --version
3.0.2
[[email protected] local]# gem install redis -v 4.0.0.rc1 --pre
2.5 建立叢集
./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
這個指令就代表把這些個redis執行個體建立為一個叢集 上面指令中的1代表主節點和從節點的比值是多少，如果12個主節點，6個從節點那麼我們的比值就是2，那麼我們是3主3從，是以這個比值是1，而且前三個一定是主節點，redis就是這樣規定的。
[[email protected] src]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
>>> Creating cluster
/usr/local/lib/ruby/gems/2.4.0/gems/redis-4.0.0.rc1/lib/redis/client.rb:459: warning: constant ::Fixnum is deprecated
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
127.0.0.1:7000
127.0.0.1:7001
127.0.0.1:7002
Adding replica 127.0.0.1:7003 to 127.0.0.1:7000
Adding replica 127.0.0.1:7004 to 127.0.0.1:7001
Adding replica 127.0.0.1:7005 to 127.0.0.1:7002
M: 446ece0004f762cde28d2637ce94718b51b50cf6 127.0.0.1:7000
slots:0-5460 (5461 slots) master
M: 70806e108250977c0e0b771fad60ff126ff1b4d0 127.0.0.1:7001
slots:5461-10922 (5462 slots) master
M: 76bbacde830abfc73ada8635c57cae0426bf370a 127.0.0.1:7002
slots:10923-16383 (5461 slots) master
S: d881644f76e1c164d2c90eacf150020d2133503e 127.0.0.1:7003
replicates 446ece0004f762cde28d2637ce94718b51b50cf6
S: 123250d99c8f85fb3a762fdd7e73e13e01ecf370 127.0.0.1:7004
replicates 70806e108250977c0e0b771fad60ff126ff1b4d0
S: 57003dbce6d92a056488fbcd3b6c0590b5e7d6cd 127.0.0.1:7005
replicates 76bbacde830abfc73ada8635c57cae0426bf370a
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 127.0.0.1:7000)
M: 446ece0004f762cde28d2637ce94718b51b50cf6 127.0.0.1:7000
slots:0-5460 (5461 slots) master
1 additional replica(s)
S: 57003dbce6d92a056488fbcd3b6c0590b5e7d6cd 192.168.8.16:7005
slots: (0 slots) slave
replicates 76bbacde830abfc73ada8635c57cae0426bf370a
S: d881644f76e1c164d2c90eacf150020d2133503e 192.168.8.16:7003
slots: (0 slots) slave
replicates 446ece0004f762cde28d2637ce94718b51b50cf6
M: 70806e108250977c0e0b771fad60ff126ff1b4d0 192.168.8.16:7001
slots:5461-10922 (5462 slots) master
1 additional replica(s)
S: 123250d99c8f85fb3a762fdd7e73e13e01ecf370 192.168.8.16:7004
slots: (0 slots) slave
replicates 70806e108250977c0e0b771fad60ff126ff1b4d0
M: 76bbacde830abfc73ada8635c57cae0426bf370a 192.168.8.16:7002
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.
檢視叢集資訊：
127.0.0.1:7001> cluster info
cluster_state:ok
cluster_slots_assigned:16384
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:6
cluster_size:3
cluster_current_epoch:39
cluster_my_epoch:34
cluster_stats_messages_sent:242027
cluster_stats_messages_received:151659
127.0.0.1:7001> cluster nodes
d881644f76e1c164d2c90eacf150020d2133503e 192.168.8.16:7003 slave 446ece0004f762cde28d2637ce94718b51b50cf6 0 1551946384970 38 connected
57003dbce6d92a056488fbcd3b6c0590b5e7d6cd 192.168.8.16:7005 slave 76bbacde830abfc73ada8635c57cae0426bf370a 0 1551946386991 39 connected
123250d99c8f85fb3a762fdd7e73e13e01ecf370 192.168.8.16:7004 slave 70806e108250977c0e0b771fad60ff126ff1b4d0 0 1551946383958 34 connected
70806e108250977c0e0b771fad60ff126ff1b4d0 192.168.8.16:7001 myself,master - 0 0 34 connected 5461-10922
76bbacde830abfc73ada8635c57cae0426bf370a 192.168.8.16:7002 master - 0 1551946385978 39 connected 10923-16383
446ece0004f762cde28d2637ce94718b51b50cf6 192.168.8.16:7000 master - 0 1551946382949 38 connected 0-5460
使用叢集的方式登入，并作測試：
[[email protected] src]# ./redis-cli -c -p 7001
127.0.0.1:7001> set test_50key test50value
-> Redirected to slot [1727] located at 192.168.8.16:7000
OK
192.168.8.16:7000> get test_50key
"test50value"
Redis Cluster 管理和測試
2.6 可能碰到的問題
1、[[email protected] src]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
/usr/local/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- redis (LoadError)
from /usr/local/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from ./redis-trib.rb:25:in `<main>'
缺少redis庫。需要安裝 redis-4.0.0.rc1.gem
2、[[email protected] src]# gem install -l redis-4.0.0.rc1.gem
ERROR: Could not find a valid gem 'redis-4.0.0.rc1.gem' (>= 0) in any repository
[[email protected] src]# gem sources -l
*** CURRENT SOURCES ***
[[email protected] src]# gem sources --add https://gems.ruby-china.org/ --remove https://rubygems.org/
Error fetching https://gems.ruby-china.org/:
SSL_connect returned=1 errno=0 state=SSLv2/v3 read server hello A: tlsv1 alert protocol version (https://gems.ruby-china.org/specs.4.8.gz)
如果出現上述錯誤可以使用http的源
[[email protected] src]# gem sources --add http://gems.ruby-china.com/ --remove https://rubygems.org/
http://gems.ruby-china.com/ added to sources
source https://rubygems.org/ not present in cache
[[email protected] src]# gem sources -l
*** CURRENT SOURCES ***
http://gems.ruby-china.com/
3、[[email protected] src]# gem install -l redis-4.0.0.rc1.gem
ERROR: Could not find a valid gem 'redis-4.0.0.rc1.gem' (>= 0) in any repository
需要更新一下源即可
[[email protected] src]# gem sources -u
source cache successfully updated
[[email protected] src]# gem install redis -v 4.0.0.rc1 --pre
Fetching redis-4.0.0.rc1.gem
Successfully installed redis-4.0.0.rc1
Parsing documentation for redis-4.0.0.rc1
Installing ri documentation for redis-4.0.0.rc1
Done installing documentation for redis after 2 seconds
1 gem installed
4、Waiting for the cluster to join一直等待解決辦法
[[email protected] src]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
>>> Creating cluster
/usr/local/lib/ruby/gems/2.4.0/gems/redis-4.0.0.rc1/lib/redis/client.rb:459: warning: constant ::Fixnum is deprecated
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
127.0.0.1:7000
127.0.0.1:7001
127.0.0.1:7002
Adding replica 127.0.0.1:7003 to 127.0.0.1:7000
Adding replica 127.0.0.1:7004 to 127.0.0.1:7001
Adding replica 127.0.0.1:7005 to 127.0.0.1:7002
M: 9b58ef401db80a4311639e021f10dafd1424a94d 127.0.0.1:7000
slots:0-5460 (5461 slots) master
M: 6b0d5f7436fe4f085313edf68cd56fa3ae9c3852 127.0.0.1:7001
slots:5461-10922 (5462 slots) master
M: 91d6a1595d78aa9719933a0e620d50bd3e723ef5 127.0.0.1:7002
slots:10923-16383 (5461 slots) master
S: 01a0e9d786980ead9d7f737c2d88cf3195c724d8 127.0.0.1:7003
replicates 9b58ef401db80a4311639e021f10dafd1424a94d
S: 9b58ef401db80a4311639e021f10dafd1424a94d 127.0.0.1:7004
replicates 6b0d5f7436fe4f085313edf68cd56fa3ae9c3852
S: 9b58ef401db80a4311639e021f10dafd1424a94d 127.0.0.1:7005
replicates 91d6a1595d78aa9719933a0e620d50bd3e723ef5
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.......................................................................................................................................................................................
需要将所有叢集中的redis.conf中的bind
由 bind 127.0.0.1 修改為 bind 192.168.8.16 127.0.0.1
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