Redis容災部署（哨兵Sentinel）
1、sentinel介紹
Redis Sentinel
Sentinel(哨兵)是用于監控redis叢集中Master狀态的工具，其已經被內建在redis2.4+的版本中
2、Sentinel作用：
1)：Master狀态檢測
2)：如果Master異常，則會進行Master-Slave切換，将其中一個Slave作為Master，将之前的Master作為Slave
3)：Master-Slave切換後，master_redis.conf、slave_redis.conf和sentinel.conf的内容都會發生改變，即master_redis.conf中會多一行slaveof的配置，sentinel.conf的監控目标會随之調換
3、Sentinel工作方式：
1)：每個Sentinel以每秒鐘一次的頻率向它所知的Master，Slave以及其他 Sentinel 執行個體發送一個 PING 指令
2)：如果一個執行個體（instance）距離最後一次有效回複 PING 指令的時間超過 down-after-milliseconds 選項所指定的值， 則這個執行個體會被 Sentinel 标記為主觀下線。
3)：如果一個Master被标記為主觀下線，則正在監視這個Master的所有 Sentinel 要以每秒一次的頻率确認Master的确進入了主觀下線狀态。
4)：當有足夠數量的 Sentinel（大于等于配置檔案指定的值）在指定的時間範圍内确認Master的确進入了主觀下線狀态， 則Master會被标記為客觀下線
5)：在一般情況下， 每個 Sentinel 會以每 10 秒一次的頻率向它已知的所有Master，Slave發送 INFO 指令
6)：當Master被 Sentinel 标記為客觀下線時，Sentinel 向下線的 Master 的所有 Slave 發送 INFO 指令的頻率會從 10 秒一次改為每秒一次
7)：若沒有足夠數量的 Sentinel 同意 Master 已經下線， Master 的客觀下線狀态就會被移除。
若 Master 重新向 Sentinel 的 PING 指令傳回有效回複， Master 的主觀下線狀态就會被移除。
4、主觀下線和客觀下線
主觀下線：Subjectively Down，簡稱 SDOWN，指的是目前 Sentinel 執行個體對某個redis伺服器做出的下線判斷。
客觀下線：Objectively Down， 簡稱 ODOWN，指的是多個 Sentinel 執行個體在對Master Server做出 SDOWN 判斷，并且通過 SENTINEL is-master-down-by-addr 指令互相交流之後，得出的Master Server下線判斷，然後開啟failover.
通俗來講就是：
redis的sentinel系統用來管理多個redis伺服器，可以實作一個功能上實作HA的叢集。該系統主要執行三個任務：
1、監控（ Monitoring ）： Redis Sentinel實時監控主伺服器和從伺服器運作狀态。
2、提醒（notification）： 當被監控的某個 Redis 伺服器出現問題時， Redis Sentinel 可以向系統管理者發送通知， 也可以通過 API 向其他程式發送通知
3. 故障遷移（failover發）：自動主從切換
4. 統一的配置管理：連接配接者詢問sentinel取得主從的位址
5、Raft分布式算法
1. 主要用途：用于分布式系統，系統容錯，以及選出領頭羊
2. 作者：Diego Ongaro，畢業于哈佛
3. 目前用到這個算法的項目有：
a. CoreOS : 見下面
b. ectd : a distributed, consistent shared configuration
c. LogCabin : 分布式存儲系統
d. redis sentinel : redis 的監控系統
Sentinel使用的Raft算法核心: 原則
1. 所有sentinel都有選舉的領頭羊的權利
2. 每個sentinel都會要求其他sentinel選舉自己為領頭羊(主要由發現redis客觀下線的sentinel先發起選舉)
3. 每個sentinel隻有一次選舉的機會
4. 采用先到先得的原則
5. 一旦加入到系統了，則不會自動清除(這一點很重要, why?)
6. 每個sentinel都有唯一的uid，不會因為重新開機而變更
7. 達到領頭羊的條件是 N/2 + 1個sentinel選擇了自己
8. 采用配置紀元，如果一次選舉出現腦裂，則配置紀元會遞增，進入下一次選舉，所有sentinel都會處于統一配置紀元，以最新的為标準。
Raft算法核心: 可視圖
Raft Visualization (算法示範)
Raft分布式算法的應用
coreos:雲計算新星 Docker 正在以火箭般的速度發展，與它相關的生态圈也漸入佳境，CoreOS 就是其中之一。CoreOS 是一個全新的、面向資料中心設計的 Linux 作業系統，在2014年7月釋出了首個穩定版本，目前已經完成了800萬美元的A輪融資。
一個簡單的主從結構加sentinel叢集的架構圖如下：
192.168.110.134（master redis，sentinel）----------->192.168.110.135（slave redis，sentinel）
| \ / |
| \ / |
| \ / |
| \ / |
| \ / |
| \ |
| \ |
| / \ |
| / \ |
| / \ |
| / \ |
192.168.110.132(sentinel)----------->192.168.110.133(slave redis，sentinel)
上圖是一主一從節點，加上兩個部署了sentinel的叢集，sentinel叢集之間會互相通信，溝通交流redis節點的狀态，做出相應的判斷并進行處理，這裡的主觀下線狀态和客觀下線狀态是比較重要的狀态，它們決定了是否進行故障轉移。
可以 通過訂閱指定的頻道資訊，當伺服器出現故障得時候通知管理者 用戶端可以将 Sentinel 看作是一個隻提供了訂閱功能的 Redis 服務
器，你不可以使用 PUBLISH 指令向這個伺服器發送資訊，但你可以用 SUBSCRIBE 指令或者 PSUBSCRIBE 指令， 通過訂閱給定的頻道來擷取
相應的事件提醒。
6、配置哨兵
1）、配置一個哨兵Sentinel的模式：
把源碼中的sentinel.conf配置檔案拷貝到指定目錄
[root@web1 ~]# mkdir /usr/local/sentinel
[root@web1 ~]# cd /usr/local/src/redis-3.2.6/
[root@web1 redis-3.2.6]# cp sentinel.conf /usr/local/sentinel/
[root@web1 redis-3.2.6]# cd /usr/local/sentinel/
[root@web1 sentinel]# vim sentinel.conf
[root@web1 sentinel]# grep -v "^#" sentinel.conf |grep -v "^$"
port 26379
dir /tmp
sentinel monitor mymaster 192.168.110.134 6379 1
sentinel down-after-milliseconds mymaster 30000
sentinel parallel-syncs mymaster 1
sentinel failover-timeout mymaster 180000
例子：
#sentinel端口
port 26380
#工作路徑
dir "/usr/local/redis-6380"
# 守護程序模式
daemonize yes
# 指明日志檔案名
logfile "./sentinel.log"
#哨兵監控的master，主從配置一樣，在進行主從切換時6379會變成目前的master端口，
sentinel monitor mymaster 192.168.137.40 6379 1
# master或slave多長時間（預設30秒）不能使用後标記為s_down狀态。
sentinel down-after-milliseconds mymaster 5000
#若sentinel在該配置值内未能完成failover操作（即故障時master/slave自動切換），則認為本次failover失敗。
sentinel failover-timeout mymaster 18000
#設定master和slaves驗證密碼
sentinel auth-pass mymaster 123456
#哨兵程式自動添加的部分
# Generated by CONFIG REWRITE
sentinel config-epoch mymaster 0
sentinel leader-epoch mymaster 1
###指明了目前群集的從庫的ip和端口，在主從切換時該值會改變
sentinel known-slave mymaster 192.168.137.40 6380
###除了目前的哨兵還有哪些監控的哨兵
sentinel known-sentinel mymaster 192.168.137.40 26379 7a88891a6147e202a53601ca16a3d438e9d55c9d
sentinel current-epoch 1
主要是這一項：
sentinel monitor mymaster 192.168.110.134 6379 2
my mymaster 後跟的是master的ip和端口
最後一個’2’代表我要啟動隻要有2個sentinel認為master下線，就認為該master客觀下線，啟動failover并選舉産生新的master。
通常最後一個參數不能多于啟動的sentinel執行個體數。
[root@web2 ~]# mkdir /usr/local/sentinel
[root@web2 ~]# cp /usr/local/src/redis-3.2.6/sentinel.conf /usr/local/sentinel/
[root@web2 ~]# cd /usr/local/sentinel/
[root@web2 sentinel]# vim sentinel.conf
[root@web2 sentinel]# grep -v "^#" sentinel.conf |grep -v "^$"
以背景啟動模式啟動兩個sentinel（哨兵）:
[root@web1 sentinel]# redis-sentinel /usr/local/sentinel/sentinel.conf &
[1] 18378
[root@web1 sentinel]# 18378:X 16 Dec 15:46:16.732 * Increased maximum number of open files to 10032 (it was originally set to 1024).
_._
_.-``__ ''-._
_.-`` `. `_. ''-._ Redis 3.2.6 (00000000/0) 64 bit
.-`` .-```. ```\/ _.,_ ''-._
( ' , .-` | `, ) Running in sentinel mode
|`-._`-...-` __...-.``-._|'` _.-'| Port: 26379
| `-._ `._ / _.-' | PID: 18378
`-._ `-._ `-./ _.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' | http://redis.io
`-._ `-._`-.__.-'_.-' _.-'
| `-._`-._ _.-'_.-' |
`-._ `-.__.-' _.-'
`-._ _.-'
`-.__.-'
18378:X 16 Dec 15:46:16.734 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
18378:X 16 Dec 15:46:16.734 # Sentinel ID is 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
18378:X 16 Dec 15:46:16.734 # +monitor master mymaster 192.168.110.134 6379 quorum 1
由上圖可以看到：
1、 哨兵已經啟動，它的id為236f14b361fc5a0dc0621cf88823ed6e6252b2f3
2、 為master資料庫添加了一個監控
3、 發現了2個slave（由此可以看出，哨兵無需配置slave，隻需要指定master，哨兵會自動發現slave）
[root@web1 sentinel]# ps aux|grep redis
root 18357 0.1 1.0 135572 2440 ? Ssl 15:40 0:00 redis-server *:6379
root 18378 0.1 1.0 133528 2572 pts/1 Sl 15:46 0:00 redis-sentinel *:26379 [sentinel]
root 18400 0.0 0.3 103244 864 pts/1 S+ 15:51 0:00 grep redis
6、從Redis當機測試
把其中一個從redis 的程序 kill掉：
[[root@web1 sentinel]# kill 18357
[root@web1 sentinel]# ps aux|grep redis
root 18378 0.1 1.0 133528 2572 pts/1 Sl 15:46 0:01 redis-sentinel *:26379 [sentinel]
root 18444 0.0 0.3 103244 864 pts/1 S+ 16:00 0:00 grep redis
30秒後哨兵的控制台輸出：
[root@web1 sentinel]# 18378:X 16 Dec 16:01:16.452 # +sdown master mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.452 # +odown master mymaster 192.168.110.134 6379 #quorum 1/1
18378:X 16 Dec 16:01:16.452 # +new-epoch 9
18378:X 16 Dec 16:01:16.452 # +try-failover master mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.470 # +vote-for-leader 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 9
18378:X 16 Dec 16:01:16.470 # +elected-leader master mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.470 # +failover-state-select-slave master mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.546 # +selected-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.546 * +failover-state-send-slaveof-noone slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.605 * +failover-state-wait-promotion slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.699 # +promoted-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.699 # +failover-state-reconf-slaves master mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.759 # +failover-end master mymaster 192.168.110.134 6379
18378:X 16 Dec 16:01:16.759 # +switch-master mymaster 192.168.110.134 6379 192.168.110.135 6379
18378:X 16 Dec 16:01:16.760 * +slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18378:X 16 Dec 16:01:46.858 # +sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
30秒後哨兵的控制台輸出：
18378:X 16 Dec 16:01:16.759 # +switch-master mymaster 192.168.110.134 6379 192.168.110.135 6379
18378:X 16 Dec 16:01:16.760 * +slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18378:X 16 Dec 16:01:46.858 # +sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
說明已經監控到剛才我人kill掉的master當機了
可以看出，slave重新已經轉換成立主庫 -sdown：說明是恢複服務。
[root@web2 sentinel]# redis-cli
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0
127.0.0.1:6379>
把192.168.110.134恢複：
[root@web1 sentinel]# redis-server /usr/local/redis/etc/redis.conf
[root@web1 sentinel]# 18378:X 16 Dec 16:06:59.825 # -sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18378:X 16 Dec 16:07:09.806 * +convert-to-slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
[root@web1 sentinel]#
[root@web1 sentinel]# ps aux|grep redis
root 18378 0.2 1.0 133528 2636 pts/1 Sl 15:46 0:02 redis-sentinel *:26379 [sentinel]
root 18487 0.1 1.0 135572 2564 ? Ssl 16:06 0:00 redis-server *:6379
root 18491 0.0 0.3 103244 864 pts/1 S+ 16:08 0:00 grep redis
192.168.110.134是作為從庫加入到複制中的（主庫不會切換過來）：
測試下：
[root@web2 sentinel]# redis-cli
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:1
slave0:ip=192.168.110.134,port=6379,state=online,offset=2835,lag=1
master_repl_offset:2835
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:2834
slave0:ip=192.168.110.134,port=6379,state=online,offset=9687,lag=0
master_repl_offset:9832
repl_backlog_histlen:9831
slave0:ip=192.168.110.134,port=6379,state=online,offset=36450,lag=0
master_repl_offset:36595
repl_backlog_histlen:36594
127.0.0.1:6379> set name2 lisi
OK
127.0.0.1:6379> set age2 22
127.0.0.1:6379> get name2
"lisi"
127.0.0.1:6379> get age2
"22"
127.0.0.1:6379>
[root@web1 sentinel]# redis-cli
role:slave
master_host:192.168.110.135
master_port:6379
master_link_status:up
master_last_io_seconds_ago:0
master_sync_in_progress:0
slave_repl_offset:73863
slave_priority:100
slave_read_only:1
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0
127.0.0.1:6379> get set2
(nil)
效果不錯：
把主庫切換回192.168.110.134
[root@web2 sentinel]# ps aux|grep redis
root 7063 0.1 1.2 135572 3116 ? Ssl 14:35 0:13 redis-server *:6379
root 7649 0.0 0.3 103244 864 pts/1 S+ 16:48 0:00 grep redis
[root@web2 sentinel]# kill 7063
[root@web1 sentinel]# 18522:X 16 Dec 16:49:05.725 # +sdown master mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:05.725 # +odown master mymaster 192.168.110.135 6379 #quorum 1/1
18522:X 16 Dec 16:49:05.725 # +new-epoch 10
18522:X 16 Dec 16:49:05.725 # +try-failover master mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:05.736 # +vote-for-leader 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 10
18522:X 16 Dec 16:49:05.736 # +elected-leader master mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:05.736 # +failover-state-select-slave master mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:05.791 # +selected-slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:05.791 * +failover-state-send-slaveof-noone slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:05.875 * +failover-state-wait-promotion slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:06.233 # +promoted-slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:06.233 # +failover-state-reconf-slaves master mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:06.331 # +failover-end master mymaster 192.168.110.135 6379
18522:X 16 Dec 16:49:06.331 # +switch-master mymaster 192.168.110.135 6379 192.168.110.134 6379
18522:X 16 Dec 16:49:06.331 * +slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
18522:X 16 Dec 16:49:36.394 # +sdown slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
切換成功
[root@web1 sentinel]# redis-cli
恢複192.168.110.135的redis：
[root@web2 sentinel]# redis-server /etc/redis.conf
127.0.0.1:6379> 18522:X 16 Dec 16:52:32.351 # -sdown slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
18522:X 16 Dec 16:52:42.305 * +convert-to-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
127.0.0.1:6379>
connected_slaves:1
slave0:ip=192.168.110.135,port=6379,state=online,offset=13653,lag=1
master_repl_offset:13667
repl_backlog_active:1
repl_backlog_first_byte_offset:2
repl_backlog_histlen:13666
1
role:slave
master_host:192.168.110.134
master_port:6379
master_link_status:up
master_last_io_seconds_ago:2
master_sync_in_progress:0
slave_repl_offset:16502
slave_priority:100
slave_read_only:1
2）、配置兩個哨兵Sentinel的模式：
[root@web1 sentinel]# grep -v "^$" /usr/local/sentinel/sentinel.conf |grep -v "^#"
port 26379
dir "/tmp"
sentinel myid 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
sentinel monitor mymaster 192.168.110.134 6379 2
sentinel config-epoch mymaster 10
sentinel leader-epoch mymaster 10
sentinel known-slave mymaster 192.168.110.135 6379
sentinel known-sentinel mymaster 192.168.110.135 26379 16286f52de2675345d1b11bc8946adc5d3f0c360
sentinel current-epoch 10
[root@web2 sentinel]# grep -v "^$" /usr/local/sentinel/sentinel.conf |grep -v "^#"
dir "/tmp"
sentinel myid 16286f52de2675345d1b11bc8946adc5d3f0c360
sentinel leader-epoch mymaster 6
sentinel known-slave mymaster 192.168.110.135 6379
sentinel known-sentinel mymaster 192.168.110.134 26379 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
sentinel current-epoch 10
主要是這一項：
sentinel monitor mymaster 192.168.110.134 6379 2
最後一個’2’代表我要啟動隻要有2個sentinel認為master下線，就認為該master客觀下線，啟動failover并選舉産生新的master。
通常最後一個參數不能多于啟動的sentinel執行個體數。
[root@web1 sentinel]# redis-sentinel /usr/local/sentinel/sentinel.conf &
[1] 18747
[root@web1 sentinel]# 18747:X 16 Dec 17:04:30.597 * Increased maximum number of open files to 10032 (it was originally set to 1024).
| `-._ `._ / _.-' | PID: 18747
18747:X 16 Dec 17:04:30.599 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
18747:X 16 Dec 17:04:30.599 # Sentinel ID is 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
18747:X 16 Dec 17:04:30.599 # +monitor master mymaster 192.168.110.134 6379 quorum 2
18747:X 16 Dec 17:05:00.659 # +sdown sentinel 16286f52de2675345d1b11bc8946adc5d3f0c360 192.168.110.135 26379 @ mymaster 192.168.110.134 6379
[root@web2 sentinel]# redis-sentinel /usr/local/sentinel/sentinel.conf &
[1] 7726
You have new mail in /var/spool/mail/root
[root@web2 sentinel]# 7726:X 16 Dec 17:04:33.835 * Increased maximum number of open files to 10032 (it was originally set to 1024).
| `-._ `._ / _.-' | PID: 7726
7726:X 16 Dec 17:04:33.836 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
7726:X 16 Dec 17:04:33.836 # Sentinel ID is 16286f52de2675345d1b11bc8946adc5d3f0c360
7726:X 16 Dec 17:04:33.836 # +monitor master mymaster 192.168.110.134 6379 quorum 2
7726:X 16 Dec 17:04:34.668 # +new-epoch 10
7726:X 16 Dec 17:05:03.836 # +sdown sentinel 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 192.168.110.134 26379 @ mymaster 192.168.110.134 6379
上面是有問題的：原因是bind 預設是僅僅監控本機和 192.168.1.1這兩個IP位址
# bind 127.0.0.1 192.168.1.1
添加： bind 0.0.0.0
就沒問題了
配置檔案：
[root@web1 ~]# grep -v "^$" /usr/local/sentinel/sentinel.conf |grep -v "^#"
bind 0.0.0.0
port 26379
dir "/tmp"
sentinel myid 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
sentinel monitor mymaster 192.168.110.135 6379 2
sentinel config-epoch mymaster 14
sentinel leader-epoch mymaster 14
sentinel known-slave mymaster 192.168.110.134 6379
sentinel known-sentinel mymaster 192.168.110.135 26379 16286f52de2675345d1b11bc8946adc5d3f0c360
sentinel current-epoch 14
主要是下面兩項：
bind 0.0.0.0
sentinel monitor mymaster 192.168.110.135 6379 2
如果設定了密碼則添加下面一項：
# sentinel auth-pass <master-name> <password>
sentinel auth-pass def_master 012_345^678-90
[root@web1 ~]# redis-sentinel /usr/local/sentinel/sentinel.conf &
[1] 1963
[root@web1 ~]# 1963:X 19 Dec 11:55:29.670 * Increased maximum number of open files to 10032 (it was originally set to 1024).
| `-._ `._ / _.-' | PID: 1963
1963:X 19 Dec 11:55:29.671 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1963:X 19 Dec 11:55:29.671 # Sentinel ID is 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
1963:X 19 Dec 11:55:29.672 # +monitor master mymaster 192.168.110.134 6379 quorum 2
上面表示啟動沒問題的：
kill掉一個從redis，觀察sentinel控制台輸出資訊：
[root@web1 ~]# kill 1912
[root@web1 ~]# ps aux|grep redis
root 1963 0.2 1.0 133528 2588 pts/0 Sl 11:55 0:00 redis-sentinel 0.0.0.0:26379 [sentinel]
root 1992 0.0 0.3 103244 864 pts/0 S+ 11:58 0:00 grep redis
[root@web1 ~]# 1963:X 19 Dec 11:59:06.906 # +sdown master mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:06.963 # +odown master mymaster 192.168.110.134 6379 #quorum 2/2
1963:X 19 Dec 11:59:06.963 # +new-epoch 14
1963:X 19 Dec 11:59:06.963 # +try-failover master mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:06.972 # +vote-for-leader 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 14
1963:X 19 Dec 11:59:06.992 # 16286f52de2675345d1b11bc8946adc5d3f0c360 voted for 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 14
1963:X 19 Dec 11:59:07.035 # +elected-leader master mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:07.035 # +failover-state-select-slave master mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:07.136 # +selected-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:07.136 * +failover-state-send-slaveof-noone slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:07.199 * +failover-state-wait-promotion slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:08.171 # +promoted-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:08.171 # +failover-state-reconf-slaves master mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:08.260 # +failover-end master mymaster 192.168.110.134 6379
1963:X 19 Dec 11:59:08.260 # +switch-master mymaster 192.168.110.134 6379 192.168.110.135 6379
1963:X 19 Dec 11:59:08.260 * +slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
1963:X 19 Dec 11:59:38.290 # +sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
另一台：
[root@web2 ~]# redis-sentinel /usr/local/sentinel/sentinel.conf &
[1] 1809
[root@web2 ~]# 1809:X 19 Dec 11:55:35.698 * Increased maximum number of open files to 10032 (it was originally set to 1024).
| `-._ `._ / _.-' | PID: 1809
1809:X 19 Dec 11:55:35.700 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1809:X 19 Dec 11:55:35.700 # Sentinel ID is 16286f52de2675345d1b11bc8946adc5d3f0c360
1809:X 19 Dec 11:55:35.700 # +monitor master mymaster 192.168.110.134 6379 quorum 2
1809:X 19 Dec 11:59:06.895 # +sdown master mymaster 192.168.110.134 6379
1809:X 19 Dec 11:59:06.999 # +new-epoch 14
1809:X 19 Dec 11:59:07.001 # +vote-for-leader 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 14
1809:X 19 Dec 11:59:08.020 # +odown master mymaster 192.168.110.134 6379 #quorum 2/2
1809:X 19 Dec 11:59:08.020 # Next failover delay: I will not start a failover before Mon Dec 19 12:05:07 2016
1809:X 19 Dec 11:59:08.284 # +config-update-from sentinel 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 192.168.110.134 26379 @ mymaster 192.168.110.134 6379
1809:X 19 Dec 11:59:08.284 # +switch-master mymaster 192.168.110.134 6379 192.168.110.135 6379
1809:X 19 Dec 11:59:08.284 * +slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
1809:X 19 Dec 11:59:38.344 # +sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
[root@web2 ~]# redis-cli
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0
127.0.0.1:6379>
恢複192.168.110.134：
[root@web1 ~]# redis-server /usr/local/redis/etc/redis.conf
[root@web1 ~]# 1963:X 19 Dec 12:14:24.393 # -sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
[root@web1 ~]# redis-cli
role:slave
master_host:192.168.110.135
master_port:6379
master_link_status:up
master_last_io_seconds_ago:1
master_sync_in_progress:0
slave_repl_offset:38769
slave_priority:100
slave_read_only:1
135上的顯示：
127.0.0.1:6379> 1809:X 19 Dec 12:14:24.105 # -sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
connected_slaves:1
slave0:ip=192.168.110.134,port=6379,state=online,offset=2404,lag=1
master_repl_offset:2404
repl_backlog_active:1
repl_backlog_first_byte_offset:2
repl_backlog_histlen:2403
也是僅僅作為從。
2）、配置三個哨兵Sentinel的模式：
[root@web2 ~]# scp redis-3.2.6.tar.gz 192.168.110.133:/root
The authenticity of host '192.168.110.133 (192.168.110.133)' can't be established.
RSA key fingerprint is 60:6c:0d:f4:3b:f8:42:b1:c9:7e:ab:c4:bc:83:d1:09.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.110.133' (RSA) to the list of known hosts.
[email protected]'s password:
redis-3.2.6.tar.gz 100% 1509KB 1.5MB/s 00:00
[root@node2 ~]# iptables -I INPUT 6 -m state --state NEW -p tcp --dport 6379 -j ACCEPT
[root@node2 ~]# iptables -I INPUT 7 -m state --state NEW -p tcp --dport 26379 -j ACCEPT
[root@node2 ~]# tar -zxvf redis-3.2.6.tar.gz -C /usr/local/src/
[root@node2 ~]# cd /usr/local/src/redis-3.2.6/
[root@node2 redis-3.2.6]# make
[root@node2 redis-3.2.6]# make install
root@node2 redis-3.2.6]# mkdir /etc/redis
[root@node2 redis-3.2.6]# mkdir -p /redis/data
[root@node2 redis-3.2.6]# mkdir -p /redis/log
2、配置主從：
[root@node2 redis-3.2.6]# grep -v "^$" /etc/redis/redis.conf |grep -v "^#"
bind *
protected-mode yes
port 6379
tcp-backlog 511
timeout 0
tcp-keepalive 300
daemonize yes
supervised no
pidfile /var/run/redis_6379.pid
loglevel notice
logfile "/redis/log/redis.log"
databases 16
save 900 1
save 300 10
save 60 10000
stop-writes-on-bgsave-error yes
rdbcompression yes
rdbchecksum yes
dbfilename dump.rdb
dir /redis/data
slaveof 192.168.110.134 6379
slave-serve-stale-data yes
slave-read-only yes
repl-diskless-sync no
repl-diskless-sync-delay 5
repl-disable-tcp-nodelay no
slave-priority 100
appendonly no
appendfilename "appendonly.aof"
appendfsync everysec
no-appendfsync-on-rewrite no
auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb
aof-load-truncated yes
lua-time-limit 5000
slowlog-log-slower-than 10000
slowlog-max-len 128
latency-monitor-threshold 0
notify-keyspace-events ""
hash-max-ziplist-entries 512
hash-max-ziplist-value 64
list-max-ziplist-size -2
list-compress-depth 0
set-max-intset-entries 512
zset-max-ziplist-entries 128
zset-max-ziplist-value 64
hll-sparse-max-bytes 3000
activerehashing yes
client-output-buffer-limit normal 0 0 0
client-output-buffer-limit slave 256mb 64mb 60
client-output-buffer-limit pubsub 32mb 8mb 60
hz 10
aof-rewrite-incremental-fsync yes
[root@node2 redis-3.2.6]# redis-server /etc/redis/redis.conf
[root@node2 redis-3.2.6]# ps aux|grep redis
root 4220 0.1 0.9 133524 2312 ? Ssl 16:36 0:00 redis-server *:6379
root 4224 0.0 0.3 103248 864 pts/0 S+ 16:36 0:00 grep redis
[root@web1 ~]# redis-cli
connected_slaves:2
slave0:ip=192.168.110.135,port=6379,state=online,offset=325246,lag=0
slave1:ip=192.168.110.133,port=6379,state=online,offset=325246,lag=0
master_repl_offset:325246
repl_backlog_histlen:325245
2、設定哨兵：
[root@node2 redis-3.2.6]# mkdir /etc/sentinel
[root@node2 redis-3.2.6]# cp sentinel.conf /etc/sentinel/
[root@node2 redis-3.2.6]# grep -v "^$" /etc/sentinel/sentinel.conf |grep -v "^#"
bind 0.0.0.0
sentinel myid fd3e2ac303fd06dfa7934718d68429dc88e3b5b8
sentinel config-epoch mymaster 15
sentinel leader-epoch mymaster 0
sentinel known-slave mymaster 192.168.110.133 6379
sentinel known-sentinel mymaster 192.168.110.134 26379 28c5f96738e4fe3335088d037a85ef47dfe9ab8f
sentinel current-epoch 15
[root@node2 redis-3.2.6]# redis-sentinel /etc/sentinel/sentinel.conf &
[1] 4240
[root@node2 redis-3.2.6]# 4240:X 18 Dec 16:48:07.492 * Increased maximum number of open files to 10032 (it was originally set to 1024).
| `-._ `._ / _.-' | PID: 4240
4240:X 18 Dec 16:48:07.494 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
4240:X 18 Dec 16:48:07.494 # Sentinel ID is fd3e2ac303fd06dfa7934718d68429dc88e3b5b8
4240:X 18 Dec 16:48:07.494 # +monitor master mymaster 192.168.110.134 6379 quorum 2
4240:X 18 Dec 16:48:07.499 * +slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
4240:X 18 Dec 16:48:07.515 * +slave slave 192.168.110.133:6379 192.168.110.133 6379 @ mymaster 192.168.110.134 6379
4240:X 18 Dec 16:48:08.295 * +sentinel sentinel 16286f52de2675345d1b11bc8946adc5d3f0c360 192.168.110.135 26379 @ mymaster 192.168.110.134 6379
4240:X 18 Dec 16:48:08.328 # +new-epoch 15
4240:X 18 Dec 16:48:09.420 * +sentinel sentinel 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 192.168.110.134 26379 @ mymaster 192.168.110.134 6379
[root@node2 redis-3.2.6]# ps aux|grep redis
root 4220 0.2 1.0 133524 2408 ? Ssl 16:36 0:03 redis-server *:6379
root 4240 0.3 1.1 133528 2696 pts/0 Sl 16:48 0:02 redis-sentinel 0.0.0.0:26379 [sentinel]
root 4264 0.0 0.3 103248 860 pts/0 S+ 17:01 0:00 grep redis
[root@web2 ~]# redis-cli -p 26379
127.0.0.1:26379> info
.... ..........
# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
sentinel_simulate_failure_flags:0
master0:name=mymaster,status=ok,address=192.168.110.134:6379,slaves=2,sentinels=2
127.0.0.1:26379> 1809:X 19 Dec 14:59:24.984 * +sentinel sentinel fd3e2ac303fd06dfa7934718d68429dc88e3b5b8 192.168.110.133 26379 @ mymaster 192.168.110.134 6379
127.0.0.1:26379>
# Server
redis_version:3.2.6
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:2f0dd1a83d7e7010
redis_mode:sentinel
os:Linux 2.6.32-431.el6.x86_64 x86_64
arch_bits:64
multiplexing_api:epoll
gcc_version:4.4.7
process_id:1809
run_id:519043c8b9e7314a71c425400d01769b3384f77c
tcp_port:26379
uptime_in_seconds:11045
uptime_in_days:0
hz:11
lru_clock:5735772
executable:/root/redis-sentinel
config_file:/usr/local/sentinel/sentinel.conf
# Clients
connected_clients:3
client_longest_output_list:0
client_biggest_input_buf:0
blocked_clients:0
# CPU
used_cpu_sys:26.71
used_cpu_user:2.31
used_cpu_sys_children:0.00
used_cpu_user_children:0.00
# Stats
total_connections_received:3
total_commands_processed:16011
instantaneous_ops_per_sec:4
total_net_input_bytes:937405
total_net_output_bytes:97572
instantaneous_input_kbps:0.26
instantaneous_output_kbps:0.02
rejected_connections:0
sync_full:0
sync_partial_ok:0
sync_partial_err:0
expired_keys:0
evicted_keys:0
keyspace_hits:0
keyspace_misses:0
pubsub_channels:0
pubsub_patterns:0
latest_fork_usec:0
migrate_cached_sockets:0
master0:name=mymaster,status=ok,address=192.168.110.134:6379,slaves=2,sentinels=3
[root@node2 redis-3.2.6]# redis-cli -p 26379
redis_build_id:98c29634d36aff37
process_id:4240
run_id:d0cf3dbc5259fa960ccf02ed101bc69bd878e26d
uptime_in_seconds:630
hz:10
lru_clock:5656509
executable:/usr/local/src/redis-3.2.6/redis-sentinel
config_file:/etc/sentinel/sentinel.conf
used_cpu_sys:1.88
used_cpu_user:0.12
total_commands_processed:1819
instantaneous_ops_per_sec:2
total_net_input_bytes:106447
total_net_output_bytes:10937
instantaneous_input_kbps:0.25
instantaneous_output_kbps:0.01
[root@node2 redis-3.2.6]# redis-cli
127.0.0.1:6379> get name
"zhangsan"
127.0.0.1:6379> get age
"20"
127.0.0.1:6379> get age1
(nil)
127.0.0.1:6379> get age2
"22"
宕掉192.168.110.134的主庫：
[root@web1 ~]# ps aux|grep redis
root 1963 0.2 1.1 133528 2716 pts/0 Sl 11:55 0:31 redis-sentinel 0.0.0.0:26379 [sentinel]
root 2068 0.1 1.4 135572 3468 ? Ssl 12:14 0:20 redis-server *:6379
root 2817 0.0 0.3 103244 864 pts/0 S+ 15:11 0:00 grep redis
[root@web1 ~]# kill 2068
root 2826 0.0 0.3 103244 864 pts/0 S+ 15:13 0:00 grep redis
[root@web1 ~]# 1963:X 19 Dec 15:13:44.721 # +sdown master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:44.776 # +odown master mymaster 192.168.110.134 6379 #quorum 3/2
1963:X 19 Dec 15:13:44.776 # +new-epoch 16
1963:X 19 Dec 15:13:44.776 # +try-failover master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:44.778 # +vote-for-leader 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 16
1963:X 19 Dec 15:13:44.797 # fd3e2ac303fd06dfa7934718d68429dc88e3b5b8 voted for 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 16
1963:X 19 Dec 15:13:44.804 # 16286f52de2675345d1b11bc8946adc5d3f0c360 voted for 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 16
1963:X 19 Dec 15:13:44.855 # +elected-leader master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:44.855 # +failover-state-select-slave master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:44.956 # +selected-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:44.956 * +failover-state-send-slaveof-noone slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:45.023 * +failover-state-wait-promotion slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:45.898 # +promoted-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:45.898 # +failover-state-reconf-slaves master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:45.963 * +slave-reconf-sent slave 192.168.110.133:6379 192.168.110.133 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:46.107 * +slave-reconf-inprog slave 192.168.110.133:6379 192.168.110.133 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:46.911 # -odown master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:47.154 * +slave-reconf-done slave 192.168.110.133:6379 192.168.110.133 6379 @ mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:47.212 # +failover-end master mymaster 192.168.110.134 6379
1963:X 19 Dec 15:13:47.212 # +switch-master mymaster 192.168.110.134 6379 192.168.110.135 6379
1963:X 19 Dec 15:13:47.213 * +slave slave 192.168.110.133:6379 192.168.110.133 6379 @ mymaster 192.168.110.135 6379
1963:X 19 Dec 15:13:47.213 * +slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
1963:X 19 Dec 15:14:17.223 # +sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.135 6379
135成了主庫：
[root@web2 ~]# redis-cli
slave0:ip=192.168.110.133,port=6379,state=online,offset=27695,lag=0
master_repl_offset:27695
repl_backlog_histlen:27694
127.0.0.1:6379> quit
[root@node2 redis-3.2.6]# redis-cli
master_last_io_seconds_ago:0
slave_repl_offset:21626
再宕掉135：
[root@web2 ~]# ps aux|grep redis
root 1809 0.2 1.1 133528 2764 pts/0 Sl 11:55 0:32 redis-sentinel 0.0.0.0:26379 [sentinel]
root 2390 0.2 1.1 135572 2872 ? Ssl 14:11 0:08 redis-server *:6379
root 2675 0.0 0.3 103244 860 pts/0 S+ 15:16 0:00 grep redis
[root@web2 ~]# kill 2390
[root@web2 ~]# ps aux|grep redis
root 1809 0.2 1.1 133528 2768 pts/0 Sl 11:55 0:32 redis-sentinel 0.0.0.0:26379 [sentinel]
root 2677 0.0 0.2 103216 640 pts/0 R+ 15:17 0:00 grep redis
[root@web2 ~]# 1809:X 19 Dec 15:17:31.230 # +sdown master mymaster 192.168.110.135 6379
1809:X 19 Dec 15:17:31.271 # +new-epoch 17
1809:X 19 Dec 15:17:31.286 # +vote-for-leader 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 17
1809:X 19 Dec 15:17:31.302 # +odown master mymaster 192.168.110.135 6379 #quorum 3/2
1809:X 19 Dec 15:17:31.302 # Next failover delay: I will not start a failover before Mon Dec 19 15:23:31 2016
1809:X 19 Dec 15:17:32.002 # +config-update-from sentinel 28c5f96738e4fe3335088d037a85ef47dfe9ab8f 192.168.110.134 26379 @ mymaster 192.168.110.135 6379
1809:X 19 Dec 15:17:32.003 # +switch-master mymaster 192.168.110.135 6379 192.168.110.133 6379
1809:X 19 Dec 15:17:32.003 * +slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.133 6379
1809:X 19 Dec 15:17:32.003 * +slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.133 6379
1809:X 19 Dec 15:18:02.004 # +sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.133 6379
1809:X 19 Dec 15:18:02.004 # +sdown slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.133 6379
133成立主庫：
127.0.0.1:6379>
[root@web1 ~]# redis-server /usr/local/redis/etc/redis.conf
[root@web1 ~]# 1963:X 19 Dec 15:21:47.745 # -sdown slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.133 6379
1963:X 19 Dec 15:21:57.749 * +convert-to-slave slave 192.168.110.134:6379 192.168.110.134 6379 @ mymaster 192.168.110.133 6379
[root@web2 ~]# redis-server /etc/redis.conf
[root@web2 ~]# 1809:X 19 Dec 15:22:34.441 # -sdown slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.133 6379
1809:X 19 Dec 15:22:44.421 * +convert-to-slave slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.133 6379
133上檢視的：
127.0.0.1:6379> 4240:X 18 Dec 17:11:18.953 # -sdown slave 192.168.110.135:6379 192.168.110.135 6379 @ mymaster 192.168.110.133 6379
connected_slaves:2
slave0:ip=192.168.110.134,port=6379,state=online,offset=24323,lag=1
slave1:ip=192.168.110.135,port=6379,state=online,offset=24470,lag=0
master_repl_offset:24470
repl_backlog_histlen:24469
[root@web1 ~]# redis-cli
master_host:192.168.110.133
slave_repl_offset:113832
[root@web2 ~]# redis-cli
slave_repl_offset:122708
sentinel一些指令介紹
要使用sentinel的指令，我們需要用redis-cli指令進入到sentinel：
1、INFO
sentinel的基本狀态資訊
2、SENTINEL masters
列出所有被監視的主伺服器，以及這些主伺服器的目前狀态
3、SENTINEL slaves
列出給定主伺服器的所有從伺服器，以及這些從伺服器的目前狀态
4、SENTINEL get-master-addr-by-name
傳回給定名字的主伺服器的 IP 位址和端口号
5、SENTINEL reset
重置所有名字和給定模式 pattern 相比對的主伺服器。重置操作清除主伺服器目前的所有狀态， 包括正在執行中的故障轉移， 并移除目前已經發現和關聯的， 主伺服器的所有從伺服器和 Sentinel 。
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