Redis的Replication（主从复制）和sentinel机制

Replication

特点：

一个Master可以有多个slave主机，支持链式复制；

Master以非阻塞方式同步数据至slave主机；

配置参数：

配置slave节点：

slaveof 主机ip 主机port

设置当本机为slav服务时，设置master服务的IP地址及端口，在Redis启 动时，它会自动从master进行数据同步；

masterauth 主机password

当master服务设置了密码保护时，slav服务连接master的密码

实验：环境：centos7.3

准备两个节点master :192.168.23.148

slave: 192.168.23.149

配置slave节点：

[root@cento7 ~]# vim /etc/redis.conf

# instance to everybody on the internet. So by default we uncomment the
# following bind directive, that will force Redis to listen only into
# the IPv4 lookback interface address (this means Redis will be able to
# accept connections only from clients running into the same computer it
# is running).
#
# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bind 127.0.0.1
bind 192.168.23.149 #为了方便看清自己的ip 又绑定一个ip
# slaveof <masterip> <masterport> #指定主机的IP地址
# If the master is password protected (using the "requirepass" configuration
# directive below) it is possible to tell the slave to authenticate before
# starting the replication synchronization process, otherwise the master will
# refuse the slave request.
#
# masterauth <master-password> # 如果主机ip有密码的话  指定主机的iP密码
#当然也可以在客户端设置

[root@cento7 ~]# redis-cli -h 192.168.23.149
192.168.23.149:6379> slaveof 192.168.23.148 6379
OK
192.168.23.149:6379> config set masterauth magedu
OK

从节点查看info信息记日志：

192.168.23.149:6379> info replication #INFO信息
# Replication
role:slave
master_host:192.168.23.148
master_port:6379
master_link_status:up
master_last_io_seconds_ago:7
master_sync_in_progress:0
slave_repl_offset:841
slave_priority:100
slave_read_only:1
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
[root@cento7 ~]# tail /var/log/redis/redis.log #日志信息
1916:S 16 Sep 15:38:52.335 * Connecting to MASTER 192.168.23.148:6379
1916:S 16 Sep 15:38:52.335 * MASTER <-> SLAVE sync started
1916:S 16 Sep 15:38:52.336 * Non blocking connect for SYNC fired the event.
1916:S 16 Sep 15:38:52.336 * Master replied to PING, replication can continue...
1916:S 16 Sep 15:38:52.337 * Partial resynchronization not possible (no cached master)
1916:S 16 Sep 15:38:52.339 * Full resync from master: 9efb89fac553574f70e5151a4f419750e47768bc:631
1916:S 16 Sep 15:38:52.438 * MASTER <-> SLAVE sync: receiving 259 bytes from master
1916:S 16 Sep 15:38:52.438 * MASTER <-> SLAVE sync: Flushing old data
1916:S 16 Sep 15:38:52.439 * MASTER <-> SLAVE sync: Loading DB in memory
1916:S 16 Sep 15:38:52.439 * MASTER <-> SLAVE sync: Finished with success

主节点的info信息记日志：

192.168.23.148:6379> INFO replication
# Replication
role:master
connected_slaves:1
slave0:ip=192.168.23.149,port=6379,state=online,offset=113,lag=0
master_repl_offset:127
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:126
192.168.23.148:6379> exit
[root@centos7 ~]# tail /var/log/redis/redis.log  # 日志信息
7195:M 16 Sep 23:50:25.961 * DB loaded from disk: 0.000 seconds
7195:M 16 Sep 23:50:25.961 * The server is now ready to accept connections on port 6379
7195:M 16 Sep 23:50:26.307 * Slave 192.168.23.149:6379 asks for synchronization
7195:M 16 Sep 23:50:26.307 * Partial resynchronization not accepted: Runid mismatch (Client asked for runid '9efb89fac553574f70e5151a4f419750e47768bc', my runid is '943571b65e4f7f2e287b69a4495193244ca473a1')
7195:M 16 Sep 23:50:26.307 * Starting BGSAVE for SYNC with target: disk
7195:M 16 Sep 23:50:26.308 * Background saving started by pid 7198
7198:C 16 Sep 23:50:26.309 * DB saved on disk
7198:C 16 Sep 23:50:26.310 * RDB: 2 MB of memory used by copy-on-write
7195:M 16 Sep 23:50:26.365 * Background saving terminated with success
7195:M 16 Sep 23:50:26.366 * Synchronization with slave 192.168.23.149:6379 succeeded

sentinel机制

作用：

用于管理多个Redis服务实现HA

1.监控主服务器Master；

2.通知；

3.自动故障转移；

协议：

流言协议、投票协议

工作过程

1）服务器自身初始化，运行于redis-server中专用于sentinel功能的代码；

2）初始化sentinel状态，根据给定的配置文件，初始化监控的master服务器列表；

3）创建连向master的连接；

配置项:

1. sentinel monitor < master-name > < ip > < redis-port> < quorum >

#连接的主节点，可以有多行，quorum表示法定票数，建议sentinel节点为奇数个

#只需要指明主节点即可，从节点会通过主节点自动获取

示例：sentinel monitor mymaster 127.0.0.1 6379 2

2. sentinel down-after-milliseconds < master-name > < milliseconds >

#判断某主节点不在线的超时时长

示例：sentinel down-after-milliseconds mymaster 30000 （单位：毫秒）

3. sentinel parallel-syncs < master-name > < numslaves >

#执行故障转移时（即刚刚设定为新主服务器时），允许最多有多少个从服务器可以向主服务器发起连接请求

示例： sentinel parallel-syncs mymaster 1

4. sentinel failover-timeout < master-name > < milliseconds >

#故障转移的超时时间，即当主服务器出现故障时，提升新的从服务器为主服务器的超时时间；

示例： sentinel failover-timeout mymaster 180000

5. sentinel auth-pass < master-name> < password>

# 连接主节点的认证密码

示例：sentinel auth-pass mymaster magedu

环境：

192.168.23.148 既为master节点 又为 sentinel节点

192.168.23.149和192.168.23.100 分别为从节点

一.配置 redis文件 /etc/redis.conf

由于从节点的配置是一样的所以这里只显示一个文件配置：

[root@cent7 ~]# vim /etc/redis.conf

#    network partition slaves automatically try to reconnect to masters
#    and resynchronize with them.
#
slaveof 192.168.23.148 6379 #从节点指向主节点ip 和 端口

# If the master is password protected (using the "requirepass" configuration
# directive below) it is possible to tell the slave to authenticate before
# starting the replication synchronization process, otherwise the master will
# refuse the slave request.
#
masterauth magedu  #主节点的密码

1.1分别查看从节点的info

从节点192.168.23.149 的信息

192.168.23.149:6379> info replication
# Replication
role:slave
master_host:192.168.23.148
master_port:6379
master_link_status:up
master_last_io_seconds_ago:3
master_sync_in_progress:0
slave_repl_offset:1051
slave_priority:100
slave_read_only:1
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

1.2 从节点192.168.23.150 的info信息

192.168.23.150:6379> info replication
# Replication
role:slave
master_host:192.168.23.148
master_port:6379
master_link_status:up
master_last_io_seconds_ago:3
master_sync_in_progress:0
slave_repl_offset:99
slave_priority:100
slave_read_only:1
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

1.3 主节点的info信息：

[root@centos7 ~]# redis-cli -h 192.168.23.148
192.168.23.148:6379> auth magedu
OK
192.168.23.148:6379> info replication
# Replication
role:master
connected_slaves:2
slave0:ip=192.168.23.150,port=6379,state=online,offset=155,lag=1
slave1:ip=192.168.23.149,port=6379,state=online,offset=155,lag=1
master_repl_offset:155
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:154

2.在主节点配置并启动sentinel机制，编辑配置文件/etc/redis-sentinel.conf

[root@centos7 ~]# vim /etc/redis-sentinel.conf
sentinel monitor mymaster 192.168.23.148 6379 1 #要连接主节点的ip和端口
sentinel down-after-milliseconds mymaster 6000 # 判断主节点不在线的超时长
sentinel failover-timeout mymaster 60000 #故障转移的超时时长

2.1 启动sentinel 服务并查看端口

[root@centos7 ~]# systemctl restart redis-sentinel.service
[root@centos7 ~]# ss -ntlp | grep "sentinel"
LISTEN     0      128          *:26379                    *:*                   users:(("redis-sentinel",pid=3480,fd=5))
LISTEN     0      128         :::26379                   :::*                   users:(("redis-sentinel",pid=3480,fd=4))

2.3 连接sentinel 需要bind主节点ip

[root@centos7 ~]# redis-cli -h 192.168.23.148 -p 26379
192.168.23.148:26379> info sentinel
# 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=odown,address=192.168.23.148:6379,slaves=0,sentinels=1
192.168.23.148:26379> sentinel masters #获取主节点的 sentinel信息
1)  1) "name"
2) "mymaster"
3) "ip"
4) "192.168.23.148"
5) "port"
6) "6379"
7) "runid"
8) ""
9) "flags"
10) "s_down,o_down,master,disconnected"
11) "link-pending-commands"
12) "0"
13) "link-refcount"
14) "1"
15) "last-ping-sent"
16) "183350"
17) "last-ok-ping-reply"
18) "183350"
19) "last-ping-reply"
20) "11658"
21) "s-down-time"
22) "177345"
23) "o-down-time"
24) "177345"
25) "down-after-milliseconds"
26) "6000"
27) "info-refresh"
28) "1505814771824"
29) "role-reported"
30) "master"
31) "role-reported-time"
32) "183350"
33) "config-epoch"
34) "0"
35) "num-slaves"
36) "0"
37) "num-other-sentinels"
38) "0"
39) "quorum"
40) "1"
41) "failover-timeout"
42) "60000"
43) "parallel-syncs"
44) "1"

2.4 获取从服务信息 注意：要在所有的redis-sentinel文件中加入密码 即

sentinel auth-pass mymaster magedu

[root@centos7 ~]# redis-cli -h 192.168.23.148 -p 26379
192.168.23.148:26379> sentinel slaves mymaster
1)  1) "name"
2) "192.168.23.150:6379"
3) "ip"
4) "192.168.23.150"
5) "port"
6) "6379"
7) "runid"
8) "5ae3e3ae957c2a3932aaaad5088acaede917e192"
9) "flags"
10) "slave"
11) "link-pending-commands"
12) "0"
13) "link-refcount"
14) "1"
15) "last-ping-sent"
16) "0"
17) "last-ok-ping-reply"
18) "759"
19) "last-ping-reply"
20) "759"
21) "down-after-milliseconds"
22) "6000"
23) "info-refresh"
24) "2310"
25) "role-reported"
26) "slave"
27) "role-reported-time"
28) "12374"
29) "master-link-down-time"
30) "0"
31) "master-link-status"
32) "ok"
33) "master-host"
34) "192.168.23.148"
35) "master-port"
36) "6379"
37) "slave-priority"
38) "100"
39) "slave-repl-offset"
40) "26696"
2)  1) "name"
2) "192.168.23.149:6379"
3) "ip"
4) "192.168.23.149"
5) "port"
6) "6379"
7) "runid"
8) "e7de20e44506d9813d1fc610c03a63d005f88855"
9) "flags"
10) "slave"
11) "link-pending-commands"
12) "0"
13) "link-refcount"
14) "1"
15) "last-ping-sent"
16) "0"
17) "last-ok-ping-reply"
18) "759"
19) "last-ping-reply"
20) "759"
21) "down-after-milliseconds"
22) "6000"
23) "info-refresh"
24) "2310"
25) "role-reported"
26) "slave"
27) "role-reported-time"
28) "12374"
29) "master-link-down-time"
30) "0"
31) "master-link-status"
32) "ok"
33) "master-host"
34) "192.168.23.148"
35) "master-port"
36) "6379"
37) "slave-priority"
38) "100"
39) "slave-repl-offset"
40) "26696"

2.5 让主节点下线 再查看主机的sentinel 信息 发现主节点已经是原来的从节点地址

[root@centos7 ~]# systemctl stop redis.service
[root@centos7 ~]# redis-cli -h 192.168.23.148 -p 26379
192.168.23.148:26379> info sentinel
# 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=odown,address=192.168.23.148:6379,slaves=2,sentinels=1
192.168.23.148:26379> sentinel masters
1)  1) "name"
2) "mymaster"
3) "ip"
4) "192.168.23.150"
5) "port"
6) "6379"
7) "runid"
8) "5ae3e3ae957c2a3932aaaad5088acaede917e192"
9) "flags"
10) "master"
11) "link-pending-commands"
12) "0"
13) "link-refcount"
14) "1"
15) "last-ping-sent"
16) "0"
17) "last-ok-ping-reply"
18) "433"
19) "last-ping-reply"
20) "433"
21) "down-after-milliseconds"
22) "6000"
23) "info-refresh"
24) "4299"
25) "role-reported"
26) "master"
27) "role-reported-time"
28) "185550"
29) "config-epoch"
30) "14"
31) "num-slaves"
32) "2"
33) "num-other-sentinels"
34) "0"
35) "quorum"
36) "1"
37) "failover-timeout"
38) "60000"
39) "parallel-syncs"
40) "1"